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Part 072 – Chemistry Previous Year Questions

Q1. Cinnabar is an ore/mineral of
(a) Lead
(b) Manganese
(c) Molybdenum
(d) Mercury
Ans: (d) Cinnabarrefers to the common bright scarlet to brick-red form of mercury sulfide (HgS) that is the most common source ore for refining elemental mercury. It is the historic source for the brilliant red or scarlet pigment termed vermilion and associated red mercury pigments.

Q2. Which among the following is not a characteristic of transition metals?

(a) Tendency to gain electrons
(b) Low electronegativity
(c) Low ionization energy
(d) Malleability
Ans: (a) The transition metals have a tendency to lose electrons. Since the electrons in the highest energy level are actually on a lower principal energy number than the ones before them, this makes it relatively easy to lose some or all of their electrons to land in stable state. When these metals form ions, the 4s electrons are always lost first; so, they form only cations (positive ions).

Q3. Ethylene is a ______ molecule.

(a) polar (b) ionic
(c) covalent (d) nonpolar
Ans: (d) Ethylene (C2H4) is a nonpolar molecule. This is because, unlike a polar molecule, it has an even distribution of electrical charges. Since, the double bond is between two carbon atoms, there is no difference in the electronegativity. This is why, the shared pair of electrons come lie in between those to carbon atoms. As a result, ethylene is a non-polar and linear molecule.

Q4. If water smells bad, then that odour can be removed by adding

(a) alum
(b) bleach
(c) activated carbon
(d) deactivated nitrogen
Ans: (c) Adding powdered activated carbon to water or using of granular activated carbon (GAC) in the water filter can remove bad taste and foul odour. Powdered activated carbon (PAC) is the preferred method when the taste and odour is moderate and infrequent. Activated carbon works by a phenomenon called “Adsorption”, which is where the odour compound is trapped inside the activated carbon and retained, but the material doing the adsorption does not change size.

Q5. The basic process taking place in nuclear reactors is

(a) Radioactivity
(b) Fission
(c) Fusion
(d) None of the above
Ans: (b) A nuclear reactor produces and controls the release of energy from splitting the atoms of uranium, known as nuclear fission. When a fissile atomic nucleus such as uranium-235 or plutonium-239 absorbs a neutron, it undergoes nuclear fission in which the heavy nucleus splits into two or more lighter nuclei. The fission process produces free neutrons and gamma photons, and releases a very large amount of energy.

Q6. Malathion is a/an

(a) insecticide (b) fumigant
(c) preservative (d) pesticide
Ans: (a) Malathion is an organophosphate (OP) insecticide that has been registered for use in the United States since 1956. It is widely used in agriculture, residential landscaping, public recreation areas, and in public health pest control programs such as mosquito eradication. It is of relatively low human toxicity.

Q7. The working of a dry cell is based on

(a) Decomposition reaction
(b) Spontaneous oxidation-reduction reaction
(c) Combination reaction
(d) Electrolysis
Ans: (d) A dry cell is a type of battery that uses a paste electrolyte, with only enough moisture to allow current to flow. It works in accordance with Faraday’s law of electrolysis. It consists of an outer case made of zinc (the negative electrode), a carbon rod in the center of the cell (the positive electrode), and the space between them is filled with an electrolyte paste. In operation the electrolyte, causes the electrons to flow and produce electricity. Ppp

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