General Science Chemistry MCQs GK UPSC SSC APSC RRB Competitive Exam Set-3

Q.1. How can we prepare Hydrogen at our home?

  1. Immersing alkali metals in water at room temperature
  2. Pouring Sulphuric acid on a copper plate
  3. Boiling zinc with caustic soda
  4. Passing electric current through rainwater

Select the correct option from the codes given below:

[A] Only 1 & 2
[B] Only 1, 3 & 4
[C] Only 2, 3 & 4
[D] 1, 2, 3 & 4

Answer: D [ 1, 2, 3 & 4]

Some key notes about Hydrogen:

  1. Hydrogen does not occur in free state in atmosphere. Hydrogen is a vital constituent of all the compounds which are known in animal and plant kingdom.
  2. Hydrogen can be prepared by the action of water or steam on metals.
  3. Hydrogen can be prepared by the action of dilute HCl or Dilute H2SO4 on the metals.
  4. Hydrogen can be prepared by boiling powdered metals like zinc, aluminum, tin and lead with concentrated solution of caustic soda.
  5. Hydrogen can be prepared by passing electric current through acidulated water.
  6. Hydrogen is a colorless and odorless gas having no taste. It is the lightest element and is practically insoluble in water.
  7. Hydrogen is prepared in lab by the action of dilute sulphuric acid on granulated zinc. If copper sulphate is added to the above reactants, the reaction speeds up.
  8. Hydrogen is neutral towards litmus.
  9. Hydrogen reacts with oxygen to form water as the only product. It reacts with chlorine gas to form hydrogen chloride gas.
  10. Hydrogen is a good reducing agent and reduces metallic oxides to metals
  11. Hydrogen is used for (i) filling weather observation balloons, (Ii) the manufacture of chemicals, (iii) the hydrogenation of oils, (iv) the extraction of metals from their oxides, and (v) cutting and welding purposes.
  12. A mixture of hydrogen and oxygen burns with a characteristic pop sound. It is a test for hydrogen.

Q.2. Which of the following are the uses of Calcium carbonate?

[A] as an antacid
[B] mild abrasive in tooth paste
[C] as a filler in cosmetics
[D] All of the above

Answer: D [All of the above]

Calcium carbonate is used as a building material in the form of marble and in the manufacture of quick lime. Calcium carbonate is also used in the manufacture of high quality paper. It finds its use as an antacid, mild abrasive in tooth paste, a constituent of chewing gum, and a filler in cosmetics.

Q.3. Which of the following molecules have a T-shape arrangement?

[A] Ozone
[B] Water
[C] Chlorine Trifluoride
[D] Sulphur dioxide

Answer: C [Chlorine Trifluoride]

Chlorine trifluoride has 10 electrons around the central chlorine atom. There are five electron pairs arranged in a trigonal bipyramidal shape and two equatorial lone pairs making the final structure T-shaped.

Q.4. Which metal is used in the Galvanization process?

[A] Tin
[B] Lead
[C] Zinc
[D] Copper

Answer: C [Zinc]

Zinc is used in galvanisation process. Galvanization is the process of applying a protective zinc coating to steel or iron, to prevent rusting.

Q.5. Which of the following is correct electronic configuration of Krypton, whose atomic number is 36?

[A] 2, 18,16
[B] 2,8,18,8
[C] 2,18,8,8
[D] 2,8,20,6

Answer: B [2,8,18,8]

Krypton is a chemical element with symbol Kr and atomic number 36. It is a member of group 18 (noble gases) elements. The electronic configuration of Krypton is [2, 8, 18, 8]

Q.6. In which among the following respects, the white Portland cement is different from the ordinary gray Portland cement?

  1. The amount of chromium, manganese, iron compounds is significantly less in white cement in comparison to gray cement
  2. The setting behaviour and strength development of white cement is significantly improved from gray cement
  3. Gypsum is used in the making of white cement and not in gray cement
  4. Production of white cement consumes significantly more energy in comparison to gray cement

Which among the above statements is / are correct?

[A] Only 2, 3 & 4
[B] Only 1, 2 & 3
[C] Only 1, 2 & 4
[D] Only 1 & 4

Answer: D [ Only 1 & 4]

Second statement is incorrect because setting behaviour and strength development of white cement is almost equivalent to grey cement. Third statement is incorrect because Gypsum is used in the making of both white cement and ordinary grey cement.

Q.7. Which of these compounds is also known as wood spirit?

[A] Ethanol
[B] Methanol
[C] Propanol
[D] None of the above

Answer: B [Methanol]

Methanol, CH3OH, also known as ‘wood spirit’. It was produced by destructive distillation of wood.

Q.8. In which of the following pairs is the repulsion greatest as per the VSEPR Theory?

[A] lone pair – lone pair
[B] lone pair – bond pair
[C] bond pair – bond pair
[D] Same for all

Answer: A [lone pair – lone pair]

The repulsion of a lone pair of electrons for another lone pair is greater than that between a bond pair and a lone pair which in turn is greater than that between two bond pairs. The correct order of repulsive force is as: lone pair – lone pair > lone pair – bond pair > bond pair – bond pair.

Q.9. Which of these non-metals is commonly used as a general anesthetic?

[A] Helium
[B] Tellurium
[C] Xenon
[D] Fluorine

Answer: C [ Xenon ]

Xenon is commonly used in medical science as a general anesthetic. It is a colorless, dense, odorless noble gas found in the Earth’s atmosphere.

Q.10. Which of the following materials can be used by a farmer to treat the too acidic soil of his fields?

  1. Quick lime (CaO)
  2. Slaked lime (Ca(OH)2)
  3. Chalk (CaCO3)

Select the correct option from the codes given below:

[A] Only 1 & 2
[B] Only 2 & 3
[C] Only 1 & 3
[D] 1, 2 & 3

Answer: D [1, 2 & 3]

Most often the soil in the fields is too acidic. If the soil is too acidic (having low pH), it is treated with materials like quicklime (calcium oxide) or slaked lime (calcium hydroxide) or chalk (calcium carbonate). Thus, a farmer should treat his soil with lime or slaked lime or chalk in his fields when the soil is too acidic.

Q.11. Which of the following can be used to treat alkali soils?

  1. Pyrite
  2. Gypsusm
  3. Organic Manure

Select the correct option from the codes given below:

[A] 1 & 2
[B] 2 & 3
[C] 1, 2 & 3
[D] None of them

Answer: C [ 1, 2 & 3]

All viz. Pyrite, Gypsum and Organic Manure can be used for reclaimation of Alkali soil.

Q.12. Which of these is NOT a compound of carbon?

[A] Acetic acid
[B] Chloroform
[C] Caustic Soda
[D] Methane

Answer: C [Caustic Soda]

Caustic soda is a compound of sodium where as Acetic acid, Chloroform and Methane are the compounds of carbon.

Q.13. What do we call the molecular orbital obtained by subtraction of atomic orbitals?

[A] Bonding orbital
[B] Anti-bonding orbital
[C] Lateral orbital
[D] Sub-orbital

Answer: B [Anti-bonding orbital]

The molecular orbital obtained by the addition of atomic orbitals is of lower energy than that of the atomic orbitals and is called a bonding orbital. The orbital obtained by subtraction of atomic orbitals is of higher energy and is called an anti-bonding orbital.

Q.14. Which of these is the reason for the temporary hardness in water?

[A] calcium bicarbonate
[B] magnesium bicarbonate
[C] Both a and b
[D] None

Answer: C [Both a and b]

Temporary hardness is a type of water hardness caused by the presence of dissolved bicarbonate minerals (calcium bicarbonate and magnesium bicarbonate).

Q.15. Tap water conducts electricity, whereas distilled water does not. This is because in comparison to distilled water, tap water has __?

[A] polarity
[B] impurity
[C] covalence
[D] surface charge

Answer: B [impurity]

Tap water contains ions (due to dissolved impurities) which help in conduction of electricity. Whereas, distilled water does not contain ions, so it can not conduct electricity.

Q.16. Which of the following is incorrect about the Inter atomic and Intermolecular Forces?

[A] Both the forces are electrical in origin
[B] Both the forces are active over short distances
[C] General shape of force-distance graph is similar for both the forces
[D] None of the above

Answer: D [None of the above]

Comparison between Inter atomic and Intermolecular Forces: (i) Both Inter atomic and Intermolecular forces are electrical in origin. (ii) Both Inter atomic and Intermolecular forces are active over short distances. (iii) General shape of force-distance graph for both the forces is similar. (iv) Both the forces are attractive up to certain distance between atoms/molecules and become repulsive when the distance between them becomes less than that value.

Q.17. What do we call the compounds having identical molecular formula but different structures?

[A] Functional isomers
[B] Structural isomers
[C] Mirror isomers
[D] Branched isomers

Answer: B [Structural isomers]

The compounds with identical molecular formula but different structures are called structural isomers.

Q.18. What are the products of the reaction when metal carbonate reacts with an acid?

[A] Salt and Hydrogen
[B] Carbon dioxide
[C] Salt, Carbon dioxide and water
[D] Salt, Carbon dioxide and Hydrogen

Answer: C [Salt, Carbon dioxide and water]

All metal carbonates and hydrogen carbonates react with acids to give a corresponding salt, carbon dioxide and water. Limestone, chalk and marble are different forms of calcium carbonate.

Q.19. Which of the following detergents represent the liquid dishwashing detergents?

[A] Anionic
[B] Cationic
[C] Non-ionic
[D] None of the above

Answer: C [Non-ionic]

Liquid dishwashing detergents are of non-ionic type. Non-ionic detergents do not contain any ion in their constitution.

Q.20. Which of the following salt is main components of the common black snake firework?

[A] Washing Soda
[B] Baking Soda
[C] Soda Lime
[D] Caustic Soda

Answer: B [Baking Soda]

Sodium bicarbonate (Baking Soda) is one of the main components of the common “black snake” firework. The effect is caused by the thermal decomposition, which produces carbon dioxide gas to produce a long snake-like ash as a combustion product of the other main component, sucrose.

Q.21. Which of the following is the unit of Strain?

[A] Newton
[B] Kg
[C] Watt
[D] None of the above

Answer: D [None of the above]

As Strain is the ratio of two like quantities, it has no dimensions and units. Strain = Change in configuration/Original configuration

Q.22. Which of the following is the correct order of the decreasing order of abundance of the elements in earth’s crust?

[A] Iron > Silicon > Oxygen >Aluminium
[B] Oxygen > Silicon > Aluminium > Iron
[C] Oxygen> Iron > Aluminium > Silicon
[D] Iron > Aluminium > Silicon > Oxygen

Answer: B [Oxygen > Silicon > Aluminium > Iron]

Oxygen is the most abundant element in the earth’s crust followed by Silicon, Aluminium and Iron. It comprises almost half of the mass of the earth’s crust.

Q.23. Which of the following is / are correct statements about Metallic oxides?

  1. Metallic oxides are also called as basic oxides
  2. Metallic oxides react with acid to give salt and water

Select the correct option from the codes given below:

[A] Only 1
[B] Only 2
[C] Both 1 & 2
[D] Neither 1 nor 2

Answer: C [Both 1 & 2]

The metallic oxides react with acids to give salts and water. It is similar to the reaction of a base with an acid, Therefore metallic oxides are normally basic oxides.

Q.24. What happens to a helium atom when it loses an electron?

[A] It becomes an alpha particle
[B] It becomes a negative helium Ion
[C] It becomes a positive Helium ion
[D] It becomes a proton

Answer: C [It becomes a positive Helium ion]

When a helium atom loses electrons, it get positive charge because the number of protons in the helium atom becomes greater than the number of electrons. When helium atom loses one electron it becomes positive ion with +1 charge.

Q.25. What kind of fertilizer is Urea?

[A] Sodium fertilizer
[B] Phosphatic fertilizer
[C] Nitrogenous fertilizer
[D] Potassium fertilizer

Answer: C [Nitrogenous fertilizer]

Fertilizers provide three primary nutrients: Nitrogen (N), Phosphorus (P) and Potassium (K). Nitrogen supports vegetative growth. Phosphorus improves roots and flowering. Potassium strengthens resistance to environmental assaults, from extreme temperatures to pest attacks. Urea is the most important nitrogenous fertilizer in the market, with the highest Nitrogen content (about 46 per cent). It is a white crystalline organic chemical compound. Urea is neutral in pH and can adapt to almost all kinds of soils. It is a waste product formed naturally by metabolizing protein in humans as well as other mammals, amphibians and some fish. Urea is widely used in the agricultural sector both as a fertilizer and animal feed additive. More than 90% of world production of urea is destined for use as a nitrogen-release fertilizer. Urea has the highest nitrogen content of all solid nitrogenous fertilizers in common use.

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