SCIENCE QUESTION

1. In the reaction PbO + C Pb + CO 
(a) Pbo is oxidised 
(b) C act as an oxidising agent 
(c) C act as a reduction agent 
(d) Reaction does not represent redox reaction. 
Ans. (c) C act as a reduction agent 

2.Why does not silver evolve hydrogen on reacting with dil H₂SO₄ ?

Ans.Silver do not evolve hydrogen  on reacting  with dil. H₂SO₄  as silver is less reactive            metal than hydrogen.

3. What happens chemically when quick lime is added to water?

Ans. When  quick lime is added to water calcium hydroxide (slaked lime)   is formed with a

hissing sound and lot of heat is evolved during  the reaction.The reaction involved is CaO(s) +     H2O(Quick Lime)  Ca(OH)2 (s) + Heat (Shaked Lime)