Science, Maths CBSE / ICSE Worksheets , Mcq's

Saturday, February 6, 2016

Physics icse class 10 smaple paper 1

Sunday, March 15, 2015

Science Worksheet

1. ‘The sex of a newborn child is a matter of chance and none of the parents may be

considered responsible for it.’ Justify this statement with the help of flow chart showing

determination of sex of a newborn. [3]

2. Tabulate two distinguishing features between acquired traits and inherited traits with

one example of each. [3]

3. Write two examples each of sexually transmitted diseases caused by (i) virus, (ii)

bacteria. Explain how the transmission of such diseases can be prevented?

4. [3]

(a) Explain the process of regeneration in Planaria.

(b) How is regeneration different from reproduction?

5. An object of height 5 cm is placed perpendicular to the principal axis of a concave lens

of focal length 10 cm. Use lens formula to determine the position, size and nature of the

image, if the distance of the object from the lens is 20 cm.(h=1.66cm)

6. [5]

(a) Write the function of placenta in females.

(b) List four ways of preventing pregnancy. State two advantages of using such

preventive methods.

7. State Snell's law of refraction of light. Write an expression to relate refractive index of a

medium with speed to light in vacuum.

8. In the figure, the parts marked A, B and C are sequentially:

9. A drop of colourless liquid is poured over blue litmus paper and it turns to red. The

colourless liquid is

(a) Potassium hydroxide solution(b) Sodium chloride solution(c) Pure water(d) Dilute hydrochloric acid

10. A student heated ferrous sulphate crystals in a test tube. He would observe that [1]

(a) The crystals start melting(b) The crystals evaporate(c) A very pungent gas is given out(d) The crystals catch fire

11. The action of water on quicklime is classified as a combination reaction because.

12. Aradhita added zinc granules in an iron sulphate solution and made a few observations.

Identify the incorrect observation.

i. Pale green solution becomes colourless ii. Black deposit seen on zinc granules

iii. Red deposit seen on zinc granules iv. Colourless solution becomes pale green

13. State with reason any two possible consequences of elimination of decomposers from the Earth.

14. . How is charcoal obtained from wood? Why charcoal is considered a better fuel than wood?

15. Describe how hydro-energy can convert into electrical energy. Write any two limitations of hydro – energy?

16. List any four advantages of water harvesting

17.

18. How will an organism be benefited if it reproduces through spores?

19. Why is vegetative propagation practiced for growing some types of plants?

20. : Define Ecology

21: Define Ecosystem. Is garden an example of Ecosystem?

22. A beam of light is allowed to pass through two beakers A and B, containing a true

solution and a colloidal solution respectively. What do you observe ? Name the phenomenon

responsible for your observation.

23. What are Rods and Cones ?

24. If the earth had no atmosphere, what change would be obsered in the length of day ?

Given reason.

25. What is cataract ? How do we rectify the same?

26. Which part of the eye can be donated after death ?

27. Why do we observe random wavering or flicking of the objects near a fire or on a

very hot day ?

28 The near point of a hypermetropic person is 75 cm from the eye. What is the power

of the lens required to enable him to read clearly a book held at 25 cm from the eye ?

29. Explain why ?

(a) Myopic person prefer to remove his spectacles while reading a book.

(b) A hypermetropic person prefer to remove the spectacles while looking at the sky.

30 (a) How do we see colours?

(b) Which cells on the retina responded to intensity of light ?

31. Explain the role played by

(i) Ciliary muscles, (ii) Aqueous humour.

32 You are given four lenses namely, bi focal

lens, convex lens, concave lens and cylindrical lens. Which lens would you prefer to correct the myopia, hypermetropia, astigmatism and presbyopia respectively?

33. A person needs a lens of power – 5.5 dioptres for correcting his distant vision. For

correcting his near vision he needs a lens of power + 1.5 dioptre.What is the focal length of

the lens required for correcting

(i) distant vision (ii) near vision?

34. A boy uses lens of focal length + 40 cm in his spectacles. Name the defect of vision he

is suffering from.

35: Define biological magnification.

36. What will happen if we kill all the organisms in one trophic level?

37. What are the problems caused by the nonbiodegradable wastes that we generate?

38. Why is the damage to the ozone layer a cause for concern?What steps are being taken

to limit this damage?

39. What is Mendel’s factor better known as?

40. Expand RNA and DNA 41. Give two functions of chromosomes 42. What do you mean by autosomes

43.“Theory of Natural Selection” was proposed by which scientist? Explain this theory briefly

Answers.

10. Very pungent gas is given out.

When ferrous sulphate crystals are heated in a test tube, pungent smell of burning

sulphur is obtained due to formation of sulphur dioxide gas.

12. A black not red deposit is seen on the zinc granules.

Pale green solution of iron sulphate turns colorless.

14. Solution:

When wood is burnt in a limited supply of oxygen, water and volatile materials present in it get removed and charcoal is left behind as the residue.

Charcoal is considered a better fuel wood because:

i) Charcoal has higher calorific value than wood. ii) It burns smoothly and produces less smoke.

iii) It leaves fewer residues. iv) It is a more compact fuel than wood and has higher percentage of combustible matter in it. v) It has lower ignition temperature than wood.

16. Four advantages of water harvesting can be listed as

Production of energy in large quantities, Increases the aquatic biomass, Increases soil fertility

Water table levels in underground is well maintained

18. The spores are covered by thick wall that protects them from unfavorable conditions like lack of

food, water or high temperature. But as the conditions become favorable these spores can grow to

produce new plant.

20. Ecology is a scientific study of the interactions between organisms and the environment.

21. An environment comprises of all living (biotic) and nonliving

(abiotic) things that occur naturally on the Earth or any of its region. All these living organisms interact with each other and their growth, reproduction and other activities are affected by the abiotic components of ecosystem.

27. The air above the fire or air above ground on hot day expands. This causes its refractive index to

change. The light passing through it is refracted. As the physical condition of air changes continues , the

refraction is not constant . This gives a wavering effect to objects near the fire or on a hot day.

28. 2.67D

33. -18.18cm,66.6cm

35 It means accumulation of poisonous materials in successive trophic levels in a food chain.

38. Steps being taken to limit this damage are (i) To protect ozone layer, the United Nations environment program forged an agreement to freeze CFC production at 1986 levels. (ii) Chlorofluoro carbons are now being replaced by hydrofluorocarbons

which do not damage the ozone layer.

41. They contain genes which are the information carriers and a link between parents and zygote.
(ii) They help in regulating the metabolism, cell differentiation and proteins synthesis

42. Autosomes are the chromosomes which are associated with the functioning of the cells and determination of characters and traits of the individual. There are22 pairs of autosomal chromosomes in human beings.

Monday, February 16, 2015

Sulphuric Acid and Nitric Acid Question Answers ICSE Biology

Question .1. (i) Give equations for the following conversions:

(a) Sulphur dioxide to Sulphur

(b) Sulphur dioxide to sodium sulphite

(c) sodium sulphite to Sulphur dioxide.

(ii) (a)Write the equation for the laboratory preparation of Sulphur dioxide from sodium sulphite.

(b) How is the SO₂ collected?

(c) What does the method of collection tell you about the density of SO₂?

(d) What do you see when SO₂ is bubbled through an acidified K₂Cr₂O₇ solution?

(iii) Write one equation in each case to show the action of Sulphur dioxide as:

(a) a reducing agent

(b) an oxidizing agent

(c) an acid anhydride.

(iv) When burning Sulphur [i.e. SO₂] reacts with H₂O, a compound is formed. Name the compound.

(v) Give the balanced equation for reaction between SO₂ and moist Cl₂.

(vi) Write a balanced equation for: SO₂ and sodium hydroxide solution. [formation of normal salt].

(vii) What type of substance will liberate Sulphur dioxide from sodium sulphite.

(viii) Write the equation for the reaction by which Sulphur dioxide is converted into sodium sulphite.

Solution:

(i) (a) 2Mg [heated] + SO₂ → 2MgO + S.

(b) 2NaOH SO₂ → Na₂SO₃ + H₂O.

Na₂SO₃ + 2HCl → 2NaCl + H₂O + SO₂.

(ii) (a) Na₂SO₃ + 2HCl → 2NaCl + H₂O + SO₂.

(b) Sulphur dioxide is collected by upward displacement of air.

(d) When SO₂ is bubbled through acidified solution of K₂Cr₂O₇, the orange colour of potassium dichromate solution turns to clear green due to formation of chromium sulphate:

K₂Cr₂O₇ + H₂SO₄ + 3SO₂ → Cr₂(SO₄)₂ + H₂O.

(iii) (a) 2HNO₃ + SO₂ → 2NO₂ + H₂SO₄.

(b) 2Mg [heated] + SO₂ → 2MgO + S.

(iv) sulphurous acid.

(v) SO₂ + Cl₂ + 2H₂O → 2HCl + H₂SO₄.

(vi) 2NaOH + SO₂ → Na₂SO₃ + H₂O.

(vii) Any mineral acid HCl, H₂SO₄ or HNO₃.

(viii) Na₂O + SO₂ → Na₂SO₃.

Question .3. (i) Name the oxide of Sulphur which reacts with water to give sulphuric acid.

(ii) In the Contact Process, the direct reaction between oxide of Sulphur and water is avoided. In this process, what does the oxide of Sulphur react with instead of water and what is the name of the product?

(iii) (a) What is the purpose of the Contact Process.

(b) Name the catalyst used in the Contact Process.

(c) Write the balanced equation for the reaction in the process which takes place in the presence of catalyst.

(iv) (a) Name the catalyst used industrially which speeds up the conversion of SO₂ and SO₃in the production of sulphuric acid in the laboratory or industrially.

(b) Write the equation for the conversion of Sulphur dioxide to Sulphur trioxide. Why does this reaction supply energy.

(c) What is the name of the compound formed between SO₃ and sulphuric acid.

(v) State the name of the process by which H₂SO₄ is manufactured. Name the catalyst used.

(vi) Name the catalyst which helps in the conversion of Sulphur dioxide to Sulphur trioxide.

(vii) In the Contact Process for the manufacture of sulphuric acid, Sulphur trioxide is not converted to sulphuric acid by reacting it with water. Instead a two-step procedure is used. Write the equations for the two steps involved.

(viii) Name the process used for the large scale manufacture of sulphuric acid.

Solution:

(i) Sulphur trioxide.

(ii) Concentrated sulphuric acid. Oleum or Pyrosulphuric acid.

(iii) (a) To manufacture sulphuric acid.

(b) Vanadium pentaoxide or platinised asbestos.

450ºC

(iv) (a) Vanadium pentaoxide or platinised asbestos.

(b) V₂O₂
2SO₂ + O₂ → 2SO₃

450ºC

The reaction supplies energy as the reaction is exothermic in nature.

(v) H₂SO₄ is manufactured by Contact Process. The catalyst used in the process is Vanadium pentaoxide or Platinised asbestos.

(vi) Vanadium pentaoxide or Platinised asbestos.

(vii) SO₃ + H₂SO₄ → H₂S₂O₇ (Oleum).

H₂S₂O₇ + H₂O → 2H₂SO₄.

(viii) Contact Process.

Question .6. (i) When H₂S reacts with oxidizing agents, what substance is always a product of the reaction.

(ii) State the colour of the precipitate formed when H₂S is bubbled through copper sulphate solution.

(iii) State how you can obtain H₂S from iron (II) sulphide.

(iv) Name a gas which smells of rotten eggs.

(v) What is observed when hydrogen sulphide gas is passed through lead acetate solution.

(vi) Select the correct compound from the list given – Ammonia, Copper oxide, Copper sulphate, Hydrogen chloride, Hydrogen sulphide, Lead bromide – which matches the description given below: The compounds smells of rotten eggs.

Solution:

(i) Sulphur.

(ii) Black precipitate of CuS.

CuSO₄ + H₂S → CuS ↓ + H₂SO₄.

(iii) Hydrogen sulphide is obtained by the action of dilute H₂SO₄ on iron (II) sulphide.

(iv) Hydrogen sulphide.

(v) When hydrogen sulphide gas is passed through lead acetate solution, black coloured precipitate of lead sulphide is formed.

Pb(CH₃COO)₂ + H₂S → PbS ↓ + 2CH₃COOH.

(vi) Hydrogen sulphide.

Question .5. (i) State why pure nitric acid takes on a yellowish brown colour when exposed to light.

(ii) Account for the yellow colour that appears in concentrated nitric acid when it is left standing in an ordinary glass bottle.

(iii) State what is observed when nitric acid is kept in a reagent bottle for a long time.

Solution:

(i) Nitric acid takes yellowish brown colour due to the presence of dissolved nitrogen dioxide.

(ii) Nitric acid slowly decomposes even at room temperature, specially in the presence of sunlight.

4HNO₃ → 4NO₂ + 2H₂O + O₂.

Liberated nitrogen dioxide dissolves in the acid and gives a yellow colour.

(iii) Brown vapours are seen in the bottle and the nitric acid turns yellowish in colour.

Question .6. (i) State the conc. acid which will oxidize Sulphur directly to H₂SO₄. Write the equation for the same.

(ii) Write a balanced equation for the reaction of Sulphur and hot concentrated nitric acid.

(iii) Dilute nitric acid is generally considered a typical acid except for its reaction with metals. In what way is dilute nitric acid different from other acids when it reacts with metals.

Solution:

(i) Hot and conc. nitric acid.

S + 6HNO₃ (Hot & Conc.) → H₂SO₄ + 2H₂O + 6NO₂.

(ii) S + 6HNO₃ (Hot & Conc.) → H₂SO₄ + 2H₂O + 6NO₂.

(iii) It acts as an oxidizing agent so hydrogen gas is not liberated. Instead NO gas and water are formed.

Question .7. (i) Write the equations for the reaction between copper and concentrated nitric acid.

(ii) Name a solution which gives nitrogen dioxide with copper.

(iii) Write a balanced for the reaction of conc. HNO₃ when added to copper turnings kept in a beaker.

(iv) Write the equation for the reaction of dilute nitric acid with copper.

Solution:

(i) Cu + 4HNO₃ (Conc.) → Cu(NO₃)₂ + 2H₂O + 2NO₂.

(ii) Nitric acid.

(iii) Cu + 4HNO₃ → Cu(NO₃)₂ + 2H₂O + 2NO₂.

(iv) 3Cu + 8HNO₃ → 3Cu(NO₃)₂ + 4H₂O + 2NO.

(vi) From the following substances, choose one in each case which matches the description given below:

Ammonium nitrate, calcium hydrogen carbonate, copper carbonate, lead carbonate, lead nitrate, potassium nitrate, sodium carbonate, sodium hydrogen carbonate, zinc carbonate.

(a) A nitrate which gives off only oxygen when heated.

(b) A nitrate which on heating decomposes into dinitrogen oxide [nitrous oxide] and steam.

(c) A nitrate which gives off oxygen and nitrogen dioxide when heated.

(a) Potassium nitrate

(b) Ammonium nitrate

Ammonia and HCL Question and Answers icse board

Q.1. (i) How is ammonia collected? Why is ammonia not collected over water ?

(ii) Which compound is normally used as a drying agent for ammonia ?

Solution:

(i) (a) Ammonia gas is lighter than air and hence collected by the downward displacement of air.[V.D. of NH₃ = 8.5, V.D. of air = 14.4]

(b) Ammonia is not collected over water since it is highly soluble in water.

[1 vol. of water dissolves about 702 vol. at 20 ºC and 1 atmos. pressure].

(ii) Quicklime [CaO]. (iii) Quicklime [CaO].

Q.2. (i) What is the purpose of Haber’s Process.

(ii) Name the gaseous inputs of the Haber’s process and state the ratio by volume in which the gases are mixed.

(iii) What is done to increase the rate of the reaction in the Haber’s Process.

(iv) Give two different ways by which the product can be separated from the reactant.

(v) Write the equation for the reaction in the Haber’s Process that forms ammonia.

(vi) State the purpose of liquefying the ammonia produced in the process.

Solution:

(i) Manufacture of Ammonia.

(ii) Nitrogen [N₂] and Hydrogen [H₂] in the ratio 1:3 by volume.

(iii) Temperature is kept low and pressure high.

(iv) (a) Liquefaction – Ammonia is easily liquefied and hence separated from nitrogen and hydrogen. (b) Dissolving in water – Ammonia is highly soluble in water and hence separated from nitrogen and hydrogen.

(v) N₂ + 3H₂ → 2NH₃ + Δ.

(vi) Ammonia is easily liquefied while nitrogen and hydrogen are not easily separated. Hence ammonia is separated from nitrogen and hydrogen.

(vii) N₂ + 3H₂ → 2 NH₃ + Δ.

Ratio of nitrogen and hydrogen is taken as 1:3. Temperature is kept 450-500ºC and pressure at 200 to 900 atmos. Catalyst iron with promoter molybdenum is used.

Q.3. (i) Write equation for the following:

(a) Burning of ammonia in oxygen (b) Catlytic oxidation of ammonia. What do you observe in (a)? Name the catalyst used in (b). In the reaction referred to in (b), the catalyst glows red hot. Why? What is the name of the industrial process which starts with the reaction referred to in .

Solution:

(i) (a) 4NH₃ + 3O₂ → 2N₂ + 6H₂O.

Pt
(b) 4NH₃ + 5O₂ → 4NO + 6H₂O + Δ .
800ºC

Observation – Dry ammonia does not burn when passed through ignited tube. When ammonia is passed through ignited tube with a passage of oxygen, ammonia burns with a greenish yellow flame forming nitrogen and water.

Catalyst – Catalyst used is Platinum. The catalyst glows since the catalytic oxidation of ammonia is an exothermic reaction.
The industrial process is known as ‘Ostwald’s Process’ for the manufacture of Nitric Acid.

Q.4. (i) Name a simple method you would employ to prepare ammonium salts in your laboratory.

(ii) What property of ammonia is demonstrated by the Fountain Experiment. Write the balanced equation for the reaction between ammonia and sulphuric acid.

(iii) Choose the correct word from the brackets for each sentence and write a balanced equation for the same.

(a) Ammonium chloride is a soluble salt prepared by ______ (precipitation, neutralization).

(b) When ammonium chloride is heated, it undergoes thermal ______ (decomposition / dissociation).

(iv) Name a gas whose solution in water is alkaline.

(v) Name the ion other than ammonium ion formed when ammonia dissolves in water.

(vi) Select the correct compound from the list given – Ammonia, Copper oxide, Copper sulphate, Hydrogen chloride, Hydrogen sulphide, Lead bromide – which matches the description given below:

Although this compound is not a metal hydroxide, its aqueous solution is alkaline in nature.

Solution:

(i) Neutralization : Ammonia in the gaseous form or in aqueous solution [NH4OH] neutralizes acids forming the respective ammonium salts.

(ii) Fountain Experiment demonstrate the high solubility of ammonia gas in water.

2NH₃ + H₂SO₄ → (NH₄)2SO₄.

(iii)(a) neutralization.

NH₄OH + HCl → NH₄Cl + H₂O

(b) dissociation.

(iv) Ammonia.

(v) Hydroxyl ion [OH^– ]

(vi) Ammonia

Q.5. (i) Write the equation for the reaction of hydrochloric acid with manganese (IV) oxide.

(ii)Name the lead compound that can be used to oxidize hydrogen chloride to chlorine.

(iii) Manganese (IV) oxide, lead (IV) oxide and red lead [Pb₃O₄] react with conc. HCl liberating chlorine. (a) What is the common property being shown by these metal oxides. (b) Write the equation for the reaction of conc. HCl with Pb₃O₄.

(iv) Write balanced equations for the reaction of manganese (IV) oxide and concentrated hydrochloric acid.

(v) Select the correct compound from the list – Ammonia, Copper oxide, Copper sulphate, Hydrogen chloride, Hydrogen sulphide, Lead bromide – which matches with the description given below : This compound can be oxidized to chlorine.

Solution:

(i) MnO₂ + 4HCl → MnCl₂ + 2H₂O + Cl₂.

(ii) Lead dioxide (PbO₂) and Red lead (Pb₃O₄).

(iii) (a) They are oxidizing agent.

(b) Pb₃O₄ + 8HCl → 3PbCl₂ + 4H₂O + Cl₂ ↑

(iv) MnO₂ + 4HCl → MnCl₂ + 2H₂O + Cl₂.

(v) Hydrogen chloride.

.
Q6. Hydrogen chloride dissolves in water forming an acidic solution. Give three distinct tests [apart from using an indicator] you would carry out with this solution to illustrate the typical properties of an acid.

(ii) (a) Hydrochloric acid reacts with active metals to liberate a colourless and odourless gas which burns with a popping sound liberating hydrogen gas.

Mg + 2HCl (dil.) → MgCl₂ + H₂.

(b) Dilute hydrochloric acid reacts with metallic carbonate and bicarbonate to liberate a colourless and odourless gas with brisk effervescence which turns lime water milky i.e. CO₂.

Na₂CO₃ + 2HCl (dil.) → 2NaCl + H₂O + CO₂

Confirmatory test :

Ca(OH)₂ + CO₂ → CaCO₃ + H₂O.

(c) Dilute hydrochloric acid reacts with metallic sulphite and bisulphate to liberate a colourless gas having smell of burning Sulphur which turns acidified potassium dichromate paper from orange to green and potassium permanganate solution from purple to colourless.

Na₂SO₃ + 2HCl (dil.) → 2NaCl + H₂O + SO₂

Q7. Write the equation for the equation for the reaction of hydrochloric acid with lead nitrate solution.

Sol. When dilute HCl is added to lead nitrate solution a white precipitate soluble in hot water but insoluble in cold water is formed.

Pb(NO₃)₂ + 2HCl → PbCl₂ ↓ + 2HNO₃.

(Q8) Write balanced chemical equation for the reaction of dilute hydrochloric acid with (a) copper oxide (b) zinc (c) calcium bicarbonate.

Sol. (iv) (a) CuO + 2HCl → CuCl₂ + H₂O

(b) Zn + 2HCl → ZnCl2 + H₂

Q.9. What must be added to sodium chloride to obtain hydrogen chloride. Write the equation for the reaction.

Solution:

(i) Concentrated sulphuric acid.

NaCl + H₂SO₄ (Conc.) → NaHSO₄ + HCl ↑

2NaCl + H₂SO₄ (Conc.) → Na₂SO₄ + 2HCl ↑