Combustion And Flame class 8th

Combustion and Flame

(Q.1)  The gas which supports combustion is-

(Q.2)  Which of the followingis a non-cumbustible substance?

( 1 mark )

(a) Coal         (b) Glass        (c) Wood        (d) Paper

(Q.3)  Combustion is a –

( 1 mark )

(a) Physical process   (b) Chemical process (c) Biological process (d) Mechanical process

(Q.4)  The substance used to extinguish fire involving electricity is-

( 1 mark )

(a) Nitrogen    (b) CO₂                (c) Water       (d) SO₂

(Q.5)  Sun produces heat and light by -

( 1 mark )

(a) Combustion         (b) Inflammation       (c) Nuclear reactions  (d) Photochemical reactions

(Q.6)  The combustion of coal dust in coal mines is-

( 1 mark )

(a) Rapid combustion.          (b) Explosion. (c) Spontaneous combustion.          (d) Non-Spontaneous combustion.

(Q.7)  Which zone of the flame is least hot?

( 1 mark )

(a) Middle zone         (b) Innermost zone             (c) Outer zone(d) Luminous zone

(Q.8)  Which gas is evolved by incomplete combustion of wood or coal?

(Q.9)  Calorific value of a substance is measured in-

(Q.10)  The substance having the highest Calorific value is-

( 1 mark )

(a) Hydrogen  (b) Bio gas     (c) LPG (d) CNG

(Q.11)  Global warming is the-

( 1 mark )

(a) decrease in the temperature of the atmosphere of earth.
(b) moderate temperature of the atmosphere of earth.
(c) increase in the temperature of the atmosphere of earth.
(d) decrease in the temperature of thehydrosphere of earth

(Q.12)  Which gas causes Global Warming?

( 1 mark )

(a)   CO      (b) SO₂                (c) O₂    (d) CO₂

(Q.13)  What do you mean by ignition temperature?

(Q.14)  Write the full forms of-
(a) CNG          (b) LPG

(Q.15)  What are inflammable substances?

(Q.16)  How is CO₂ able to control fire?

(Q.17)  What are the essential requirements for producing fire? On which principle the fire extinguisher works?

(Q.18)  Define-
1. Spontaneous combustion.

2. Rapid combustion.

(Q.19)  What are the characteristics of an ideal fuel?

(Q.20)  The temperature of the hottest zone of candle is around

( 1 mark )

(a) 1000⁰C.     (b) 1200⁰C.    (c) 1500⁰C.     (d) 1800⁰C.

(Q.68)  When clothes of a person catch fire, his body is covered with blanket to

( 1 mark )

(a) stop the supply of O₂.               (b) make him feel comfortable.
(c) save him from any injury.         (d) hold his body properly.