The figure given below shows the relative contribution of four green house gases to global warming .

(i) Identify the gases A and C.
(ii) Why are these four gases called the greenhouse gases ?

What are green house gases ?

Name two green house gases.

Why are the Gr-18 elements called as inert gases ?

State the contribution (in percentage) of the various greenhouse gases mentioned below towards global warming. (i) Methane (CH_4) (ii) Nitrogen oxide (N_2O)

Write four characteristic properties of noble gases.

Mention one use of each of four noble gases .

(i) Write the balanced equations to represent what happens when (a) acidified potassium permanganates reacts with hydrogen sulphide ? (b) acidified potassium dichromate solution reacts with iron (II) solution (ionic equation) ? (ii) The figure given below illustrates the first ionisation enthalpies of first, second and third series of transition elements. (a) Which series amongst the first, second and third series of transition elements have the highest first ionisation enthalpy and Why ? (b) Why there is a fall in IE_(2) from Cr to Mn and from Cu to Zn ? Explain.