chemistry : Elements Compounds and Mixtures class 9

Elements Compounds and Mixtures

1.    Which of the following is an  element ,  a compound or  a mixture . Give reason for answer

a.     Chlorine     b. sulphur  c. sea water         d. CO2        e. bronze

2.    Define the following

a.     Molecule   b.      Atomicity   c.  Compound

3.    Name         a) A diatomic element b) Tetra atomic element  c)  Liquid metal                  d) mealleable metal     e) lustrous non metal  f) liquid non-metal

4.    Give difference between Mixture and Compound?

5.    What is the difference between homogeneous and heterogeneous mixture?

6.    Why air is considered a mixture

7.    What is a true solution?

8.    Give properties of suspension?

9.    Define electrophoresis?

10.                       How will you separate

a.     Sulphur and carbon

b.    Sand and sugar

c.     Iodine and common salt

d.    Naphthalene and common salt

e.     Iron fillings, iodine and sugar

11.                       On what factors does the separation of mixture depends

12.                       How will you separate two immiscible liquids?

13.                       What do you understand by chromatography?

14.                       What are metalloids? Give examples

15.                       Name three metals which show exceptions to the properties of metals

Acid Base cbse icse worksheet

Acid Base

Q1: The most commonly used indicator in laboratory is

(a) Methyl Orange    (b) Litmus      (c) Phenolphtalein   (d) Universal Indicator

Q2: Olfactory indicators are:

(a) Clove        (b) Turmeric  (c) Soap         (d) Rose Petals

Q3: An element common to all acids is

(a) Chlorine   (b) Nitrogen  (c) Oxygen    (d) Hydrogen

Q4: Metal carbonate on reaction with dilute acid release

(a) CO₂              (b) CO                        (c) H₂O           (d) H₂

Q5 (Teachers FA manual): ln general, salts

(a) are ionic compounds     (b) contain hydrogen ions

(c) contain hydroxide ions (d) turn litmus red

Q6: On passing excess of CO₂ gas in an aqueous solution of calcium carbonate, milkiness of the solution

(a) persists     (b) fades        (c) deepens    (d) disappears

Q7(FA manual): When magnesium and hydrochloric acid react, they produce

(a) Oxygen and magnesium chloride                    (b) Chlorine and magnesium oxide

(c) Hydrogen and magnesium chloride    (d) Hydrogen and magnesium oxide

Q8:  Dissolution of acid or base in water is 

(a) Exothermic          (b) Endothermic       (c) Violent     (d) None of these

Q9: Water contains more H+ ions than OH- ions. In this case, water is

(a) neutral      (b) basic         (c) acidic       (d) cannot say.

Q10: When an acid reacts with a base what compounds are formed?

(a) water only           (b) metal oxides only          (c) a salt only            (d) a salt and water

Q11: Which of the following is a property of an acid?

(a) slippery feel        (b) non-reactive       (c) sour taste (d) strong color        

Q12: On diluting an acid concentration of H+ per unit volume

(a) increases  (b) decreases (c) remains unaffected        (d) depends on type of acid used.

Q14: Tartaric acid is the constituent of

(a) bleaching powder           (b) baking powder    (c) washing powder (d) plaster of paris

Q15: A solution turns blue litmus red. Its pH value is likely to be

(a) 4    (b) 7    (c) 9    (d) 12

Q17: Which gas is produced by reaction of base with metal ?

(a) Carbon dioxide   (b) Dioxygen             (c) Dihydrogen         (d) Dinitrogen

Q18: Acid + Metal-oxide  → ?

(a) Base + Water      (b) Salt + Water        (c) Base + Salt                      (d) Metal + Salt

Q19: Which of the following is a weak acid?

(a) Hydrochloric Acid         (b) Nitric Acid          (c) Acetic Acid      (d) Sulphuric Acid

Q20: An indicator is what type of compound?

(a) reducing agent    (b) strong base or acid                     (c) weak base or aci (d) salt

Q21: Which of the following is strong acid ?

(a) Acetic acid          (b) Citric acid           (c) Nitric acid           (d) Oxalic acid

Q22: Name the organic acid present in tomato

(a) Tartaric Acid       (b) Malic Acid                      (c) Lactic Acid          (d) Oxalic Acid

Q23: Fill in the blanks.

(a) Turmeric, clove, rose petals are ______  _____ .

(b) Acids  reacts with   bases to form ________ and

(c) The term pH was coined by _______ .

(d) Turmeric turns ___________ in basic medium.

(e)  _______________ is used in softening water.

(f) Strong acids show ______ ionisation while weak acids show _______ ionisation.

(g) Calcium Sulphate hemihydrate is popularly known as _____ ___ _____.

(h) Acids contain the hydrogen (H⁺) as the only ______ _______.

(i) Bases contain the Oxide (O^2-) or hydroxide (OH^-) radical as the only _______ radical.

Q27: You have been provided with three test tubes. One of them contains distilled water and the other two contain an acidic solution and a basic solution, respectively. If you are given only red litmus paper, how will you identify the contents of each test tube?

Q28: Why should curd and sour substances not be kept in brass and copper vessels?

Q29: Why vinegar is used in pickling?

Q30: Why phenolphthalein is considered acid base indicator?

Q32 Metal compound A reacts with dilute hydrochloric acid to produce effervescence. The gas evolved extinguishes a burning candle. Write a balanced chemical equation for the reaction if one of the compounds formed is calcium chloride.

Q33. Why do HCl, HNO₃ , etc., show acidic characters in aqueous solutions while solutions of compounds like alcohol and glucose do not show acidic character?

Q34: Why does an aqueous solution of an acid conduct electricity?

Q35: Why should acids be handled with care?

Q36: Why does dry HCl gas not change the colour of dry litmus paper

Q38: What is an amphoteric substance?

Q40:  What are organic acids? Give two examples

Q41: What are mineral acids? Give two examples

Q42: What is the chemical name of Bleaching powder? How it is prepared? List its uses.

Q44: What is gypsum?

Q46: Tooth enamel is one of the hardest substance in our body. How does it undergo damage due to the eating of chocolates and sweets? What should we do to prevent it?

Q: Why does tooth decay start when the pH of the mouth is lower than 5.5?

Maths Fractions Decimals Algebric Expression class 7

Simplify

1.  2 z + u + 4, when z = 7 and u = 3	2.   x − z − 7, when x = 3 and z = 7
3.   5 + 4a, when a = 7	4.   7 q z2, when q = 10 and z = 4

Express each phrase as an algebraic expression.

1.   12 more than the quotient of 16 and a number j	2.   10 times the sum of a number q and 49
3.   2 less than the product of 3 and a number r	4.   2 increased by a number z
5.   a fourth of the difference of 38 and a number s	6.   31 multiplied by a number t

Q 22 In the adjoining figure, name the following pairs of angles:

   

(i)     Obtuse vertically opposite angles

(ii)    Adjacent complement angles

(iii)   Equal supplementary angles

(iv)   Unequal supplementary angles

(v)    Adjacent angles that do not form a linear pair.

Short Questions

1.     An angle is greater than 45 . Will its

complement be an angle greater than 45 or equal to 45  or less than 45 ?

2.     State true or false: If measure of an angle is 90° then its supplement angle will be greater than 90°.

3.     State true or false: Two acute angles form a linear pair.

4.     Fill in the blank : If two adjacent angles are complementary they form a ______

5.     How many litres are there in 755 ml ? 

6.     1/3 is the  reciprocal of ______. 

7.     Fill in the blank given below by any one of >, < or = 
 2.005 __ 2.05 

8.     Write an equivalent  fraction of .

9.     A player played 14 games. Out of which he won 8 games. Write the fraction of the games he won

10.                        ___has no reciprocal.

Answer the following

1.     Raghu has 175 sweets out of which he gives one fifth part part to his sister and out of the remaining he gives  two seventh part to his youngest brother. How many sweets are left with him.

2.      

3.