Chemistry - Study Mode

[#216] Which one of the following species has the highest bond order, shortest bond length and maximum bond strength?
Correct Answer

(B) O + 2

Explanation

Solution: O + 2 has the highest bond order, shortest bond length and maximum bond strength.

[#217] The number of hydrogen bonds between guanine and cytosine in DNA is
Correct Answer

(B) 3

Explanation

Solution: There are two hydrogen bonds between adenine and thymine (A=T) and three hydrogen bonds between cytosine and guanine (G=C).

[#218] The constituents of automobile exhaust that can cause cancer is/are :
Correct Answer

(C) Polycyclic hydrocarbons

Explanation

Solution: Car exhaust fumes contain many different things. Some of them are harmful to our health. This question asks about the parts that can cause cancer. Option A: Oxides of nitrogen: These are gases that can irritate your lungs, but they are not directly known to cause cancer. Option B: Carbon monoxide: This is a poisonous gas that stops your body from getting enough oxygen. It is dangerous but doesn't cause cancer directly. Option C: Polycyclic hydrocarbons: These are a group of chemicals found in car exhaust. They are known to cause cancer. Option D: Lead: Lead is a heavy metal, and it's toxic. While it can cause other health problems, it is not directly a known cancer-causing agent in the way polycyclic hydrocarbons are. Therefore, the correct answer is C, Polycyclic hydrocarbons.

[#219] The acid rain destroys vegetations because it contains
Correct Answer

(D) Sulphuric acid

Explanation

Solution: Acid rain is a formed due to the mixing of oxides of several harmful gases with the rain. Acid rain formation result from both natural sources, such as volcanoes and decaying vegetation, and man-made sources, primarily emissions of sulfur dioxide and nitrogen oxides resulting from fossil fuel combustion. These gases react in the atmosphere with water, oxygen, and other chemicals to form various acidic compounds.
When this rain falls on the soil, the soil becomes acidic. Also, the leaves get destroyed and germinating seeds get corroded. Plants experience stunted growth. Thus, vegetation is destroyed.
So, the correct answer is option D.

[#220] Of the following, which one pollutes the air of a big city ?
Correct Answer

(C) Lead

Explanation

Solution: Lead pollution primarily came from cars in the past. Today, lead pollution primarily comes from lead smelters, metal processing plants and incinerators. Deposits of lead in soil can harm both humans and animals by absorbing it into a body.