MEDIUM
8th CBSE
IMPORTANT
Earn 100
Burning more and more fossil fuels creates an imbalance in the natural carbon cycle as well as in the natural water cycle. Give reasons.
Important Questions on Carbon and its Compounds
MEDIUM
8th CBSE
IMPORTANT
Tiny diamonds find applications in coating the tips and edges of cutting tools. Which properties of diamonds are made use of for this purpose?
MEDIUM
8th CBSE
IMPORTANT
Explain the role of baking soda as a leavening agent and as an antacid.
MEDIUM
8th CBSE
IMPORTANT
An oxide of a bivalent metal on heating with coke gives a compound X and a gas Y. The gas Y reacts with chlorine gas to give a poisonous gaseous compound. X undergoes hydrolysis to give a hydrocarbon Z with two carbon atoms. Identify the compounds X, Y and Z. Also, give the reactions involved.
MEDIUM
8th CBSE
IMPORTANT
Graphite is used as a solid lubricant. Give reasons.
MEDIUM
8th CBSE
IMPORTANT
How does a dry powder type fire extinguisher work?
HARD
8th CBSE
IMPORTANT
A naturally occurring minerals of sedimentary rocks on heating to high temperatures decomposes giving a solid 'A' and a gas. The solid on dissolution in water undergoes chemical reactions which is associtated with hissing sound and the solution appears to be boiling. Compound 'B' formed during this reaction on long standing forms a layer of white powder. When excess is passed through this milky white solution, a clear solution is formed again. Identify the substances and justify the above observations. Give reasons wherever required.
MEDIUM
8th CBSE
IMPORTANT
In the manufacture of silicon carbide by Acheson process, sawdust is used along with sand and coke in the electric furnace. What is the main purpose of using sawdust as one of the constituents of the mixture?
MEDIUM
8th CBSE
IMPORTANT
The genuineness of a pearl can be verified by dipping it in lemon juice. Why?
