Fill in the blanks:
$(1)$ The types of smog are ..... and ..... .
$(2)$ Ozone in the air reacts with hydrocarbons to form ...... and ...... .
$(3)$ Harmful ultraviolet rays from the sun cause a type of skin cancer known as ...... .
$(4)$ Chlorofluorocarbon compounds are also called .......... .

Two statements are given below.
Statement-$I$: In dry cleaning,the solvent $Cl_2C=CCl_2$ was earlier used and now it is replaced by liquified $CO_2$.
Statement-$II$: In bleaching of paper,$H_2O_2$ was used earlier and now it is replaced by chlorine gas.
Correct answer is

If the $pH$ of water increases above ......,the effectiveness of chlorination in water is reduced.

Which of the following statements is not correct?

The deposition of $X$ and $Y$ on ground surfaces is referred to as wet and dry depositions,respectively. $X$ and $Y$ are:

Given below are two statements:
Statement $I$: Chlorofluorocarbons breakdown by radiation in the visible energy region and release chlorine gas in the atmosphere which then reacts with stratospheric ozone.
Statement $II$: Atmospheric ozone reacts with nitric oxide to give nitrogen and oxygen gases,which add to the atmosphere.
For the above statements choose the correct answer from the options given below :