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All questions of Chemistry for BPSC (Bihar) Exam

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H2O is liquid and H2S is a gas because
  • a)
    oxygen forms stronger hydrogen level than sulphur.
  • b)
    oxygen is less electronegative than sulphur.
  • c)
    atomic radius of oxygen is less than that of sulphur.
  • d)
    atomic radius of oxygen is greater than that of sulphur.
Correct answer is option 'A'. Can you explain this answer?

Rahul Rathore answered
In h2o there is hydrogen bonding because oxygen has a high electronegativity(only second to flourine). so, the hydrogen atoms from other molecules of water forms a hydrogen bonds with oxygen resulting in intermolecular hydrogen bonding. ... therefore at room temperature h2o is aliquid and h2s is a gas.

Hydrogen bomb is based on the principle of
  • a)
    controlled fusion reaction
  • b)
    uncontrolled fusion reaction
  • c)
    controlled fission reaction
  • d)
    uncontrolled fission reaction
Correct answer is option 'B'. Can you explain this answer?

Rithika Menon answered
Thermonuclear fusion, or hydrogen bombs explode with enormous power using uncontrolled self-sustaining chain fusion reactions. Deuterium and tritium, under extremely high temperatures, form helium providing the energy. D + T → 4He + n In principle, a mixture of D, T and 6Li heated to very high temperature and confined to a high density will start a chain fusion reaction, liberating an enormous amount of energy.

Which one of the following pairs is correctly matched?
  • a)
    Silver iodide — Horn silver
  • b)
    Silver chloride — Artificial rain
  • c)
    Zinc phosphide — Rat poison
  • d)
    Zinc sulphide — Philosopher’s wool
Correct answer is option 'C'. Can you explain this answer?

Kunal Roy answered
Cerargyrite, also called Horn Silver, gray, very heavy halide mineral composed of silver chloride (AgCl); it is an ore of silver. Tiny particles of silver iodide are sprayed on a cloud from an aeroplane. The particles attract water drops from the cloud. When they form a drop that is large enough, it starts raining. Zinc phosphide is an inorganic compound that is used in pesticide products as a rodenticide.. Zinc oxide is also known as philosopher's wool.

Enriched uranium is
  • a)
    Uranium rods kept under special shield
  • b)
    Natural uranium in which the component of radioactive isotope U235 is artificial increased
  • c)
    Natural uranium mixed with thorium
  • d)
    Uranium rods coated with chromium
Correct answer is option 'B'. Can you explain this answer?

Palak Nambiar answered
Enriched uranium is a type of uranium in which the percent composition of uranium-235 has been increased through the process of isotope separation. Enriched uranium is a critical component for both civil nuclear power generation and military nuclear weapons. The International Atomic Energy Agency attempts to monitor and control enriched uranium supplies and processes in its efforts to ensure nuclear power generation safety and curb nuclear weapons proliferation.

Living in the atmosphere of CO is dangerous because it
  • a)
    Reduces organic matter of tissues
  • b)
    Dries up the blood
  • c)
    Combined with O2 present inside to form CO2
  • d)
    Combines with haemoglobin and makes it incapable of absorbing oxygen
Correct answer is option 'D'. Can you explain this answer?

Devanshi Chavan answered
When CO is not ventilated it binds to haemoglobin, which is the principal oxygencarrying compound in blood; this produces a compound known as carboxyhaemoglobin. The traditional belief is that carbon monoxide toxicity arises from the formation of carboxyhaemoglobin, which decreases the oxygen-carrying capacity of the blood and inhibits the transport, delivery, and utilization of oxygen by the body.

Which of the following pairs is/are correctly matched?
1. Isotopes : Atoms with same atomic number but different atomic mass.
2. Isobars : Atoms with same number of neutrons but different atomic number.
3. Isotones : Atoms with same mass number but different atomic number.

Q. Select the correct answer using the codes given below :
  • a)
    1, 2 and 3
  • b)
    1 only
  • c)
    1 and 2 only
  • d)
    2 only
Correct answer is option 'B'. Can you explain this answer?

Aarya Choudhary answered
Isotopes are variants of a particular chemical element: while all isotopes of a given element share the same number of protons and electrons, each isotope differs from the others in its number of neutrons. For example, carbon-12, carbon-13 and carbon-14 are three isotopes of the element carbon with mass numbers 12, 13 and 14 respectively. The atomic number of carbon is 6, which means that every carbon atom has 6 protons, so that the neutron numbers of these isotopes are 6, 7 and 8 respectively

Domestic cooking gas consists of mostly
  • a)
    Methane and ethane
  • b)
    Liquified butane and isobutane
  • c)
    Ethylene and carbon monoxide
  • d)
    Hydrogen and acetylene
Correct answer is option 'B'. Can you explain this answer?

Nikhil Ghosh answered
Introduction to Domestic Cooking Gas
Domestic cooking gas primarily refers to the fuel used in household cooking appliances. This gas is commonly supplied in a liquefied form for ease of storage and transportation.
Composition of Domestic Cooking Gas
- Domestic cooking gas mainly consists of liquefied petroleum gas (LPG), which is a mixture of:
- Butane: A four-carbon alkane that is a key component of LPG.
- Isobutane: The branched-chain isomer of butane, also present in significant amounts.
Why Option B is Correct
- Efficiency: Butane and isobutane are efficient fuels that produce a high energy output with relatively low emissions when burned.
- Storage and Transportation: These gases can be liquefied at moderate pressures, making them easy to store in cylinders.
- Safety and Convenience: LPG is odorized for safety, allowing users to detect leaks through a distinct smell.
Comparison with Other Options
- Option A (Methane and Ethane): Although methane is a significant component of natural gas, domestic cooking gas is primarily LPG, not a mix of methane and ethane.
- Option C (Ethylene and Carbon Monoxide): These gases are not typically used for cooking due to their toxic nature and are not part of domestic cooking gas.
- Option D (Hydrogen and Acetylene): While hydrogen is a clean fuel, acetylene is not used for cooking due to its instability and safety concerns.
Conclusion
In summary, the correct answer is option B because domestic cooking gas primarily consists of liquefied butane and isobutane, which are safe, efficient, and practical for household cooking purposes.

Which one among the following statements regarding the properties of mixtures and compounds is not correct?
  • a)
    A mixture shows the properties of its constituents but the properties of a compound are entirely different from its constituents
  • b)
    A mixture may be homogeneous or heterogeneous but a compound is a homogeneous substance
  • c)
    The constituents of a mixture can be separated by physical methods but those of a compound cannot be separated by physical methods
  • d)
    Energy is either absorbed or evolved during the preparation of a mixture but not in the preparation of a compound
Correct answer is option 'D'. Can you explain this answer?

Dipika Gupta answered
The compound is always formed by absorption or evolution of energy but no energy is released or absorbed during the formation of mixture.

Consider the following statements:
Nitrogen is an essential constituent of
1. soils
2. animals
3. plants

Q. Which of the statements given above is/are correct ?
  • a)
    3 only
  • b)
    1 and 3 only
  • c)
    1, 2 and 3
  • d)
    1 and 2 only
Correct answer is option 'C'. Can you explain this answer?

Aarav Saini answered
Understanding the Importance of Nitrogen
Nitrogen is a crucial element that plays a significant role in the ecosystem. The statements regarding its presence in soils, animals, and plants highlight its essential nature. Let's break down each statement to understand why the correct answer is option 'C'.
1. Nitrogen in Soils
- Nitrogen is a vital nutrient found in soils, primarily in the form of organic matter and various nitrogenous compounds.
- It is a key component for the growth of crops, as it contributes to soil fertility and health.
2. Nitrogen in Animals
- Animals require nitrogen for the synthesis of amino acids, which are the building blocks of proteins and essential for various bodily functions.
- Nitrogen is present in the form of proteins and nucleic acids in animals, making it an essential constituent.
3. Nitrogen in Plants
- Plants absorb nitrogen from the soil in the form of nitrates and ammonium, which are critical for their growth and development.
- Nitrogen is a key element in chlorophyll, the molecule responsible for photosynthesis, thus influencing plant health and productivity.
Conclusion
Given that nitrogen is indeed an essential constituent of soils, animals, and plants, all three statements are correct. Therefore, the correct answer is:
c) 1, 2 and 3
This highlights the interconnectedness of nitrogen in various forms of life and its importance in maintaining ecological balance.

The order of appearance of the following with increasing temperature during the refining of crude oil is __________
  • a)
    Kerosene, gasoline, diesel
  • b)
    Diesel, gasoline, kerosene
  • c)
    Gasoline, kerosene, diesel
  • d)
    Gasoline, diesel, kerosene
Correct answer is option 'C'. Can you explain this answer?

Saanvi Reddy answered
Petroleum products are usually grouped into three categories: light distillates (LPG, gasoline, naphtha), middle distillates (kerosene, diesel), heavy distillates and residuum (heavy fuel oil, lubricating oils, wax, asphalt). Hence, the correct option would be: Gasoline, kerosene, diesel.

Helium is preferred to hydrogen in air balloons because it
  • a)
    is cheaper
  • b)
    is less dense
  • c)
    has greater lifting power
  • d)
    does not form an explosive mixture with air
Correct answer is option 'D'. Can you explain this answer?

Anshul Ghosh answered
Hydrogen combines with oxygen with explosive force in the presence of a spark.Helium is an inert gas that will not burn or explode, so is much safer to use in balloons instead of hydrogen.

What happened when a hard boiled egg after shelling is immersed in saturated brine?
  • a)
    It shrinks
  • b)
    It grows in size
  • c)
    Its size remains unchanged
  • d)
    it initially grows in size and then shrinks.
Correct answer is option 'C'. Can you explain this answer?

Nidhi Pillai answered
When hard boiled egg after shelling is immersed in saturated brine, its size remains same. Due to coagulation of inner liquid there is no flow of solvent molecules across the membrane.

Q.Which of the following substances is/are ozone depleting?
1. Chlorofluorocarbons
2. Halons
3. Carbon tetrachloride
  • a)
    1 only
  • b)
    1 and 2 only
  • c)
    2 and 3 only
  • d)
    1, 2 and 3
Correct answer is option 'D'. Can you explain this answer?

Sagar Chakraborty answered
All the three substances are responsible for ozone layer depletion in different ways. Which are: CFC—mostly used in refrigeration, air conditioning and heat pump systems. Halons—used historically as fire suppression agents and fire fighting, but now only allowed in very limited situations. Carbon tetrachloride (tetrachloromethane)—limited solvent used in laboratories and chemical and pharmaceutical industries.

Hydrofluoric acid is not kept in glass bottles because it reacts with
  • a)
    visible light
  • b)
    sodium oxide of glass
  • c)
    aluminium oxide of glass
  • d)
    silicon dioxide of glass
Correct answer is option 'D'. Can you explain this answer?

Aashna Nambiar answered
Hydrofluoric acid is one of the most dangerous acids known. It needs to be treated differently then even strong acids like sulphuric and hydrochloric. HF reacts with many materials, therefore, avoid contact with glass, concrete, metals, water, other acids, oxidizers, reducers, alkalis, combustibles, organics and ceramics.

The inexhaustible source of energy of the stars is due to
  • a)
    conversion of hydrogen to helium
  • b)
    conversion of helium to hydrogen
  • c)
    decay of radioactive elements
  • d)
    excess of oxygen that helps burning and release of energy
Correct answer is option 'A'. Can you explain this answer?

Raksha Khanna answered
The energy released from the collapse of the gas into a star causes the centre of the star to become extremely hot. When the core is hot enough, nuclear fusion commences. Fusion is the process where two hydrogen atoms combine to form a helium atom, releasing energy. The fusion reaction is a very efficient process, releasing a huge amount of energy. This is because a single helium atom contains less mass than two hydrogen atoms. The excess mass is released as energy.

In cold weather, aquatic animals survive even when water to the top layer of the lake freezes into ice because
  • a)
    they can breathe in ice
  • b)
    they have enough of accumulated oxygen inside them
  • c)
    their body structure is such that they can survive without oxygen.
  • d)
    water has highest density of 4°C so underneath the top layer of ice there is layer of water
Correct answer is option 'D'. Can you explain this answer?

Aravind Chatterjee answered
In cold countries, when the temperature of fresh water reaches 4°C, the layers of water near the top in contact with cold air continue to lose heat energy and their temperature falls below 4°C. On cooling below 4°C, these layers do not sink but may rise up as fresh water has a maximum density at 4°C. Due to this, the layer of water at 4°C remains at the bottom and above this layers of water 3°C, 2°C, 1°C and 0°C are formed. Because ice is a poor conductor of heat, it does not absorb heat energy from the water beneath the layer of ice which prevents the water freezing. Thus, aquatic creatures survive in such places.

Which one of the following is NOT correct?
  • a)
    Theory of evolution was propounded by Charles Darwin.
  • b)
    The breaking apart of the nucleus of an atom is called fusion.
  • c)
    Dry ice is nothing but solid carbon dioxide.
  • d)
    Telephone was invented by Graham Bell.
Correct answer is option 'B'. Can you explain this answer?

Mihir Mukherjee answered
Theory of Evolution
- Charles Darwin is credited with the formulation of the theory of evolution through natural selection, which explains how species adapt and evolve over time.
Fusion vs. Fission
- The statement in option B incorrectly describes a nuclear process.
- Fission is the process where the nucleus of an atom splits into smaller parts, usually releasing a significant amount of energy.
- Fusion, on the other hand, is the process where two light atomic nuclei combine to form a heavier nucleus, which also releases energy.
Dry Ice
- Dry ice is indeed solid carbon dioxide (CO2), used primarily as a refrigerant or for creating fog effects.
Invention of the Telephone
- Alexander Graham Bell is recognized for inventing the first practical telephone, revolutionizing communication.
Conclusion
- Therefore, the incorrect statement is option B, as it confuses the terms fusion and fission, misrepresenting fundamental nuclear physics. Understanding these concepts is vital, especially in scientific fields, and highlights the importance of precise language in science.

Biogas mainly consists of
  • a)
    Carbon dioxide and hydrogen
  • b)
    Hydrogen and methane
  • c)
    Carbon dioxide and methane
  • d)
    Hydrogen and oxygen
Correct answer is option 'C'. Can you explain this answer?

Kaavya Sarkar answered
Bio gas is primarily methane (CH4) and carbon dioxide (CO2) and may have small amounts of hydrogen sulphide (H2S), moisture and siloxanes.

Match List–I with List–II and select the correct answer using the codes given below :
  • a)
    A
  • b)
    B
  • c)
    C
  • d)
    D
Correct answer is option 'A'. Can you explain this answer?

Dipika Gupta answered
These compounds are used in the manufacture of the following products. Cellulose nitrate- Gun powder, Potassium Sulphate- Fertiliser, Potassium salts of fatty acids- Soft soap, Calcium oxide- Glass.

Consider the following statements and select the correct code.
Assertion (A): A chemical reaction becomes faster at higher temperature.
Reason (R): At higher temperature, molecular motion becomes more rapid.
  • a)
    Both A and R are true and R is the correct explanation of A.
  • b)
    Both A and R are true, but R is not correct explanation of A.
  • c)
    A is true, but R is false.
  • d)
    A is false, but R is true.
Correct answer is option 'A'. Can you explain this answer?

Avi Sengupta answered
The rates of most reactions increase with a rise in temperature. Raising the temperature increases the fraction of molecules having very high kinetic energies. These are the ones most likely to react when they collide. The higher the temperature, the larger the fraction of molecules that can provide the activation energy needed for reaction.

Match List-I with List-II and select the correct answer from the codes given below


  • a)
    A
  • b)
    B
  • c)
    C
  • d)
    D
Correct answer is option 'A'. Can you explain this answer?

Meghana Shah answered
Quarks have fractional electric charge values– either 1/2 or 2/3 times the elementary charge. The positron has an electric charge of +1e, a spin of 1/2, and has the same mass as an electron. A neutrino is an electrically neutral, weakly interacting elementary subatomic particle with halfinteger spin. All evidence suggest that neutrinos have mass but that their mass is tiny even by the standards of subatomic particles. Their mass has never been measured accurately.

Match List-I with List-II and select the correct answer from the codes given below:

  • a)
    A
  • b)
    B
  • c)
    C
  • d)
    D
Correct answer is option 'D'. Can you explain this answer?

Nilanjan Banerjee answered
Nickel silver, also known as German silver, is a copper alloy with nickel and often zinc. Solders are typically made from tin or lead or a combination of both in the ratio of 63:37 respectively. Calcium hypochlorite, also known as bleaching powder, is a chemical compound with formula Ca(ClO)2. It is widely used for water treatment and as a bleaching agent. This chemical is considered to be relatively stable and has greater available chlorine than sodium hypochlorite (liquid bleach). Hypo solution is the abbreviation for sodium thiosulphate or sodium hyposulphite, a chemical used to fix the image on photographic film after it has been developed.

Match List-I with List-II and select the correct answer from the codes given below:

  • a)
    A
  • b)
    B
  • c)
    C
  • d)
    D
Correct answer is option 'A'. Can you explain this answer?

Shreya Desai answered
Manganese is essential to iron and steel production. At present, steel making accounts 85 to 90% of the total demand, most of the total demand. Manganese is a key component of low-cost stainless steel formulations and certain widely used aluminium alloys. Limestone can be used in constructing buildings. It can be used for making cement and mortar. Limestone is used to make glass and even used to make roads. Bauxite is the mineral ore of aluminium which is used in the manufacture of cans, airplanes, sporting and electronic equipment and home appliances. The Wright Brother's first airplane to fly in 1903 only was able to get off the ground because they modified its engine with aluminium in order to reduce its weight. Without the ability of the strong aluminium, alloys to withstand the huge pressures and stresses involved, high altitude flying would not be conceivable. In fact, aluminium comprises about 80% of an aircraft’s unladen weight. The element copper is used extensively as an electrical conductor, for the making of electrical wire.

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