Practice MCQ Questions and answers on Chemistry-GK

Bicarbonate buffer is the most important buffer system in blood plasma (generally in the extracellular fluid). This buffer consists of weak acid H₂CO₃(pK1 = 6,1) and conjugated base HCO₃^- (bicarbonate).

Although ozone (O3) is present in small concentrations throughout the atmosphere, most ozone (about 90%) exists in the stratosphere, in a layer between 10 and 50 km above the surface of the earth. This ozone layer performs the essential task of filtering out most of the sun's biologically harmful UV radiation.

Bleaching agents are substances used to whiten or remove color.
Option A: Alcohol - Alcohol is a good solvent and disinfectant, but it doesn't effectively remove color.
Option B: Carbon Dioxide - Carbon dioxide is a gas we breathe out and is used in fire extinguishers and to make fizzy drinks. It doesn't have bleaching properties.
Option C: Chlorine - Chlorine is widely used as a bleaching agent because it's very effective at breaking down the chemical compounds that cause color. Think of cleaning products and swimming pools – chlorine is often used in those.
Option D: Sodium Chloride - Sodium chloride is actually common table salt (NaCl). It's important for our bodies but not a bleaching agent.
Therefore, chlorine is the most common and effective bleaching agent among the options provided.

Most hydrogen atoms have nuclei that consist of a single proton, but a small fraction (about 0.015 percent) of the hydrogen atoms that occur in Nature have one neutron in addition to the proton in their nuclei.

The heat required to raise the temperature of a body by 1 K is called thermal capacity. In other words, when q is the heat supplied to the body and the temperature raises by 1 K, then the thermal capacity of body is q.

Nuclear particles responsible for holding all nucleons together are mesons. To account for the binding forces between like particles such as proton and proton or neutron and neutron, Kemmer suggested the existence of a neutral meson (π0).

Balanced chemical equation:
P₄ + 5O₂ --------> P₄O₁₀
1 mol 5 mol 1 mol
124g 160g 284g
Here limiting reagent is P₄.
So, 124g of P₄ produce P₄O₁₀ = 284g
Therefore,
1.33g of P₄ produce P₄O₁₀ = (284/124)*1.33
= 3.05g

n-heptane is defined as the zero point of the octane rating scale. 2,2,4-Trimethylpentane has an octane rating of 100, whereas n-heptane has an octane rating of 0. The octane number is based on an arbitrary scale which is a measure of its ability to resist knocking, as it burns on combustion.

Although nickel is the preferred catalyst for hydrogenation of fats and oils, the use of other metals such as palladium, platinum, ruthenium, and rhodium leads to products with less trans compounds.

The most abundant rare gas in the atmosphere is Argon (Ar).