Environmental Chemistry — Page 2 | NEET Chemistry

Q11

The presence of soluble fluoride ion upto 1 ppm concentration in drinking water, is :

A safe for teeth

B harmful to skin

C harmful for teeth

D harmful to bones

Correct Answer

Option A

Solution

Fluoride (F–) ion conc upto 1 ppm makes the enamel of teeth much harder by converting.

Q12

Water sample is called cleanest on the basis of which one of the BOD values given below :

A 11 ppm

B 15 ppm

C 3 ppm

D 21 ppm

Correct Answer

Option C

Solution

BOD is the biological oxygen demand.

Cleanest water sample will have BOD value equal to 3 ppm as clean water could have BOD value of less than 5 ppm whereas highly polluted water could have BOD value of 17 ppm or more.

Q13

Which among the following pairs has only herbicides?

A Aldrin and Dieldrin

B Sodium chlorate and Aldrin

C Sodium arsinate and Dieldrin

D Sodium chlorate and sodium arsinite

Correct Answer

Option D

Solution

Both sodium chlorate and sodium arsenate behave as herbicide.

Q14

The water quality of a pond was analyzed and its BOD was found to be 4. The pond has :

A Very clean water

B Highly polluted water

C Water has high amount of fluoride compounds

D Slightly polluted water

Correct Answer

Option A

Solution

A clean water would have BOD value less than 5 ppm.

Q15

Which of the following are the Green house gases? A. Water vapour B. Ozone C. I

_2

D. Molecular hydrogen Choose the most appropriate answer from the options given below :

A A and D only

B A and B only

C B and C only

D C and D only

Correct Answer

Option B

Solution

Green house gases are $\mathrm{CO}_2, \mathrm{CH}_4$ , water vapour, nitrous oxide, $\mathrm{CFC}_8$ and ozone.

Q16

Match with . .tg .tg Pollutant Source

List - I		List - II
(A)	Microorganisms	(I)	Strip mining
(B)	Plant nutrients	(II)	Domestic sewage
(C)	Toxic heavy metals	(III)	Chemical fertilizer
(D)	Sediment	(IV)	Chemical factory

A A-II, B-III, C-IV, D-I

B A-II, B-I, C-IV D-III

C A-I, B-IV, C-II, D-III

D A-I, B-IV, C-III, D-II

Correct Answer

Option A

Solution

Pollutant Source

\begin{array}{ll} \text{ Microorganisms } & \rightarrow \text{ Domestic sewage } \\ \text{ Plant nutrients } & \rightarrow \text{ Chemical fertilizers } \\ \text{ Toxic heavy metals } & \rightarrow \text{ Chemical factory } \\ \text{ Sediment } & \rightarrow \text{ Strip mining } \end{array}

Q17

Peroxyacetyl nitrate (PAN), an eye irritant is produced by :

A classical smog

B acid rain

C photochemical smog

D organic waste

Correct Answer

Option C

Solution

Photochemical smog produce chemicals such as formaldehyde, acrolein and peroxyacetyl nitrate(PAN).

Q18

The concentration of dissolved oxygen (DO) in cold water can go upto :

A 14 ppm

B 16 ppm

C 8 ppm

D 10 ppm

Correct Answer

Option D

Solution

In cold water, dissolved oxygen (DO) can reach a concentration upto 10 ppm.

Q19

The molecule that has minimum /no role in the formation of photochemical smog, is :

A CH2 = O

B O3

C N2

D NO

Correct Answer

Option C

Solution

Photochemical smog is produced when ultraviolet light from sun reacts with NO , O3 and hydrocarbon in atmosphere.

Q20

A water sample has ppm level concentration of the following metals : Fe = 0.2; Mn = 5.0; Cu = 3.0; Zn = 5.0. The metal that makes the water sample unsuitable for drinking is :

A Cu

B Mn

C Fe

D Zn

Correct Answer

Option B

Solution

When Mn present in water with concentration 0.05 ppm or more than this then the water is unsuitable for drinking.

Here given concentration for Mn is 5.0, which is grater than 0.05 that is why it is Mn makes water unsuitable for drinking.

For other metal water is suitable for drinking when concentration for Fe = 0.2 ppm and for Cu = 3.0 ppm and for Zn = 5.0 ppm.