Carbon and its Compounds — Science STD 10 — Question

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

An element ‘A’ has two electrons in the outermost shell of its atom and combines with an element ‘B’ having seven electrons in the outermost shell, forming the compound AB₂. The compound when dissolved in water conducts electric current. Giving reasons, state the nature of chemical bond in the compound.

How can diamonds be made artificially? How do synthetic diamonds differ from natural ones?

Draw the structures for the following compounds:

1. Ethanal.
2. Propanal.
3. Butanal.
4. Pentanal.

Give the molecular formula of butane and mention the names of its two isomers. Name one fuel which contains both these isomers.

Why compounds like petrol, coal, etc generate heat or light or both on combustion?

Write the chemical equation of the reaction which takes place when iron reacts with dilute sulphuric acid. What happens when the gas produced is ignited with a burning matchstick?

Potatoes grow well on Anhad’s farm which has soil with a pH of 5.5. Anhad decides to add lot of lime to soil so that he can grow broccoli in the same farm:

1. Do potatoes grow better in acidic or alkaline soil?
2. Does broccoli grow better in acidic or alkaline soil?

Name one metal and one non-metal that exist in liquid state at room temperature. Also name two metals having melting point less than 310K (37°C).

You are given three solutions A, B and C with pH values 2, 10 and 13 respectively. Write which solution has more hydrogen ions concentration among the three and state the nature ‘acidic or basic’ of each solution.