Practical Work — CHEMISTRY STD 9 — Question

Name three gases which destroy ozone layer.

State the sources and effects of the following gas:
Methane

Describe the role of carbon dioxide in greenhouse effect.

State the original colour of the following substance and colour of residue obtained after heating.
Lead nitrate

An atom A has the mass number 40 and atomic number 18. An atom B has the mass number 40 and atomic number 20.
(a) What is the electronic configuration of A?
(b) What its the electronic configuration of B?
(c) Are A and B isotopes of the same clement?
(d) Which amongst A and B is a metal?

Account for the following fact:
Though lead is above hydrogen in the activity series, it does not react with dilute hydrochloric acid or dilutes sulphuric acid.

(a) Name two metals which react with cold water to form hydrogen. Write the balanced chemical equations.
(b) Name two metals which react with steam and displace hydrogen. Write the balanced chemical equations.

Potassium (at No.19) and chlorine (at No.17) react to form a compound. Explain the formation of the compound on the basis of:
Reducing agent

State (i) the three variables for gas laws and (ii) SI units of these variables.

(a) What are solubility curves?
(b) State two applications of solubility curves.