Bihar Police GK in English
41. The density of water is exactly 1 g/cc at which temperature?
A) 0°C
B) 4°C
C) 25°C
D) 100°C
B) 4°C
Explanation: The density of water is exactly 1 g/cc at 4°C. At this temperature, water reaches its maximum density.
42. Who is the founder of the quantum theory of radiation?
A) Einstein
B) Bohr
C) Planck
D) S.S. Bose
C) Planck
Explanation: Max Planck is considered the founder of the quantum theory of radiation. He proposed that energy is emitted in discrete packets called quanta.
43. Why is the outer bottom part of cooking utensils left black?
A) It is difficult to clean daily
B) Black surfaces are good conductors of heat
C) Black surfaces are poor conductors of heat
D) Black surfaces are good absorbers of heat
D) Black surfaces are good absorbers of heat
Explanation: Black surfaces are good absorbers of heat, which helps in cooking food faster by absorbing more heat.
44. Gas thermometers are more sensitive than liquid thermometers because gas?
A) Expands
B) Is lighter
C) Has lower specific heat
D) Has higher specific heat
C) Has lower specific heat
Explanation: Gas thermometers are more sensitive because gases have lower specific heat capacity, allowing them to respond more quickly to changes in temperature.
45. Sulfuric acid is?
A) Monobasic
B) Dibasic
C) Tribasic
D) Tetrabasic
B) Dibasic
Explanation: Sulfuric acid (H₂SO₄) is a dibasic acid because it can donate two protons (H⁺) per molecule in an aqueous solution.
46. Which alloy is used for making heating elements in electric heating appliances?
A) Solder
B) Alloy Steel
C) Nichrome
D) German Silver
C) Nichrome
Explanation: Nichrome is an alloy composed of nickel and chromium, and it is commonly used for making heating elements in electric heaters due to its high resistance and ability to withstand high temperatures.
47. What is the estimated pH of lemon juice?
A) Equal to 7
B) Prediction is not possible
C) Less than 7
D) Greater than 7
C) Less than 7
Explanation: Lemon juice is acidic in nature, and the pH of an acidic substance is less than 7.
48. During electrorefining, where does the pure metal collect?
A) Vessel
B) Electrolyte
C) Cathode
D) Anode
C) Cathode
Explanation: In the process of electrorefining, the pure metal is deposited at the cathode, while impurities settle at the anode or are left in the electrolyte solution.
49. Which of the following is the most powerful coagulant?
A) Zinc Chloride
B) Aluminum Chloride
C) Barium Chloride
D) Magnesium Sulfate
B) Aluminum Chloride
Explanation: Aluminum chloride is a strong coagulant commonly used in water treatment to remove impurities by causing them to clump together.
50. Which chemical is used for cloud seeding in artificial rain?
A) Silver Nitrate
B) Potassium Bromide
C) Silver Iodide
D) Potassium Nitrate
C) Silver Iodide
Explanation: Silver iodide is widely used for cloud seeding, which involves dispersing it into clouds to encourage the formation of ice crystals, thereby inducing precipitation.