Class – X
Time allowed: 3 hours
Maximum Marks: 90
The question paper comprises of two sections, A and B. you are to attempt both the sections. All questions are compulsory.
Questions 1 to 3 are one mark question of section A.
Questions 4 to 6 carry two marks each of section A.
Questions 7 to 18 carry three marks each of section A.
Questions 19 to 24 carry five marks each of section A.
Questions 25 to 33 carry one mark each of section B.
Questions 34 to 36 are two marks each of section A..
Section – A
Identify the category in which the organisms using carbon dioxide and water as food are placed. Define 1 Watt.
Why is a solar cooker painted black from outside?
Name the chemical which is injected into the skin of a person during
a) Honey bee’s sting
b) The nettle leaf sting. How can the effect of these stings be neutralized?
Rahul has been collecting copper coins and silver coins. One day he observed a green coating on copper coins and a black coating on silver coins. State the chemical phenomenon responsible for these coatings and also write chemical names of each coating.
How is our brain double-protected against injuries and shocks?
Identify the type of chemical reactions in the following processes:
a) Barium chloride solution is mixed with copper sulphate solution and a write precipitate is formed. b) On heating copper powder in a china dish, the surface of copper powder become black.
c) On heating green ferrous sulphate crystals, reddish brown solid is left as residue and a gas having smell of burning Sulphur is evolved.
d) Iron nails when left dipped in blue copper sulphate solution become brownish in colour and blue colour of copper sulphate solution fades away.
e) Quicklime reacts vigorously with water releasing large amount of heat.
f) Silver nitrate solution reacts with sodium chloride solution and a white precipitate is