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Chemistry MCQs | Objective Type Questions | MCQs SET-2
1.Which of the following causes the rusting of iron?
- Oxidation
- Reduction
- Chemical reaction with oxygen
- Chemical reaction with CO2
Select the correct answer from the codes given below:
Correct Answer: D [Only 1 and 3]
Notes:
Rust is composed of iron oxides. In colloquial usage, the term is applied to red oxides, formed by the reaction of iron and oxygen in the presence of water or air moisture. When impure (cast) iron is in contact with water, oxygen, or other strong oxidants, or acids, it rusts. If salt is present, for example in seawater or salt spray, the iron tends to rust more quickly, as a result of electrochemical reactions. Supporting the process of rusting.
Rust is composed of iron oxides. In colloquial usage, the term is applied to red oxides, formed by the reaction of iron and oxygen in the presence of water or air moisture. When impure (cast) iron is in contact with water, oxygen, or other strong oxidants, or acids, it rusts. If salt is present, for example in seawater or salt spray, the iron tends to rust more quickly, as a result of electrochemical reactions. Supporting the process of rusting.
2.Nucleons are regarded as composites sub-particles known as:
Correct Answer: B [Quarks]
Notes:
In quantum chromodynamics, nucleons are regarded as composites of three quarks (elementary particles) and pions are composites of two quarks. According to EOB’s rules, nucleons move as fermions while pions move as bosons.
In quantum chromodynamics, nucleons are regarded as composites of three quarks (elementary particles) and pions are composites of two quarks. According to EOB’s rules, nucleons move as fermions while pions move as bosons.
3.A solution is:
Correct Answer: A [a homogeneous mixture of two or more substances]
Notes:
A homogeneous mixture of two or more substances uniformly dispersed throughout a single phase is called solution. In such a mixture, a solute is a substance dissolved in another substance, known as a solvent. The solution more or less takes on the characteristics of the solvent including its phase, and the solvent is commonly the major fraction of the mixture.
A homogeneous mixture of two or more substances uniformly dispersed throughout a single phase is called solution. In such a mixture, a solute is a substance dissolved in another substance, known as a solvent. The solution more or less takes on the characteristics of the solvent including its phase, and the solvent is commonly the major fraction of the mixture.
4.Which element is most electronegative among Arsenic, Nitrogen and Phosphorus?
Correct Answer: A [Nitrogen]
Notes:
Electronegativity is a measure of the ability of an atom to attract the electrons when the atom is part of a compound. Since metals have few valence electrons, they tend to increase their stability by losing electrons to become cations. Consequently, the electronegativities of metals are generally low. Electronegativity of following elements is:
Electronegativity is a measure of the ability of an atom to attract the electrons when the atom is part of a compound. Since metals have few valence electrons, they tend to increase their stability by losing electrons to become cations. Consequently, the electronegativities of metals are generally low. Electronegativity of following elements is:
- Nitrogen: 3.04
- Phosphorous: 2.19
- Arsenic: 2.18
5.Mass Number is always equal to:
Correct Answer: D [sum of number of protons and number of neutrons]
Notes:
Mass number is the sum of the numbers of protons and neutrons present in the nucleus of an atom. The mass number is different for each different isotope of a chemical element. This is not the same as the atomic number (Z) which denotes the number of protons in a nucleus, and thus uniquely identifies an element.
Mass number is the sum of the numbers of protons and neutrons present in the nucleus of an atom. The mass number is different for each different isotope of a chemical element. This is not the same as the atomic number (Z) which denotes the number of protons in a nucleus, and thus uniquely identifies an element.
6.Which of the toxic heavy metals is found in modern tannery industries?
Correct Answer: C [Chromium]
Notes:
Chromium is mainly found in waste from the chrome tanning process; it occurs as part of the retanning system and is displaced from leathers during retanning and dyeing processes. This chrome is discharged from processes in soluble form; however, when mixed with tannery waste waters from other processes (especially if proteins are present), the reaction is very rapid. Precipitates are formed, mainly protein-chrome, which add to sludge generation. If chrome discharges are excessive, the chromium might remain in the solution. Even in low concentrations, it has a toxic effect upon daphnia, thus disrupting the food chain for fish life and possibly inhibiting photosynthesis.
Chromium is mainly found in waste from the chrome tanning process; it occurs as part of the retanning system and is displaced from leathers during retanning and dyeing processes. This chrome is discharged from processes in soluble form; however, when mixed with tannery waste waters from other processes (especially if proteins are present), the reaction is very rapid. Precipitates are formed, mainly protein-chrome, which add to sludge generation. If chrome discharges are excessive, the chromium might remain in the solution. Even in low concentrations, it has a toxic effect upon daphnia, thus disrupting the food chain for fish life and possibly inhibiting photosynthesis.
7.Which metal is the heaviest in periodic table among the following?
Correct Answer: A [Os]
Notes:
The densest chemical element is Osmium a metal. It has a density of around 22 grams per cubic centimeter, about twice the density of lead.
The densest chemical element is Osmium a metal. It has a density of around 22 grams per cubic centimeter, about twice the density of lead.
8.Which of the following are requirements for producing fire?
- Fuel
- Air
- Heat
Select the correct answer from the codes given below:
Correct Answer: D [All of the above ]
Notes:
The essential requirements for producing fire are: fuel, air (to supply oxygen) and heat (to raise the temperature of the fuel beyond the ignition temperature).
The essential requirements for producing fire are: fuel, air (to supply oxygen) and heat (to raise the temperature of the fuel beyond the ignition temperature).
9.The chemical name of ‘Common salt’ is:
Correct Answer: A [Sodium chloride]
Notes:
Sodium chloride, also known as common salt, table salt or halite, is an ionic compound with the formula NaCl, representing equal proportions of sodium and chloride. It is the most responsible for the salinity of the ocean and of the extracellular fluid of many multicellular organisms. As the major ingredient in edible salt, it is commonly used as a condiment and food preservative.
Sodium chloride, also known as common salt, table salt or halite, is an ionic compound with the formula NaCl, representing equal proportions of sodium and chloride. It is the most responsible for the salinity of the ocean and of the extracellular fluid of many multicellular organisms. As the major ingredient in edible salt, it is commonly used as a condiment and food preservative.
10.Bleaching powder is prepared by passing:
Correct Answer: A [Chlorine over slaked lime]
Notes:
Calcium hypochlorite (bleaching powder) is manufactured by the calcium process
Calcium hypochlorite (bleaching powder) is manufactured by the calcium process
- 2Ca(OH)2 {slaked lime} + 2Cl2 {Chlorine} —> Ca(OCl)2 {Bleaching powder} + 2H20.
is actually a mixture of calcium hypochlorite and the basic chloride with some slaked lime.
