56. Out of Chlorine, Phosphorus, Ozone, and Krypton, the elements having the lowest and highest atomicities are respectively:
(a) Chlorine & Ozone
(b) Krypton & Ozone
(c) Krypton & Phosphorus
(d) Chlorine & Phosphorus
Answer:
(c) Krypton & Phosphorus
Explanation:
Atomicity is the number of atoms in a molecule. Krypton is a noble gas and is monoatomic (1). Phosphorus forms tetratomic molecules (4). Chlorine () is diatomic (2) and Ozone () is triatomic (3).
57. Aqua regia is a freshly prepared mixture of concentrated hydrochloric acid () and concentrated nitric acid () in the ratio of:
(a) 1:3
(b) 3:1
(c) 2:3
(d) 3:2
Answer:
(b) 3:1
Explanation:
Aqua regia is a highly corrosive mixture prepared by combining 3 parts concentrated Hydrochloric acid () with 1 part concentrated Nitric acid ().
58. The two elements that exist in a liquid state at room temperature () are:
(a) Mercury & Bromine
(b) Mercury & Chlorine
(c) Iodine & Bromine
(d) Gallium & Mercury
Answer:
(a) Mercury & Bromine
Explanation:
Mercury (a metal) and Bromine (a non-metal) are the only two elements on the periodic table that are liquid under standard room temperature conditions.
59. Which of the following metals is so soft that it can be cut with a knife?
(a) Iron
(b) Aluminium
(c) Copper
(d) Sodium
Answer:
(d) Sodium
Explanation:
Alkali metals like Sodium (Na) and Potassium (K) are extremely soft metals that can easily be cut with a regular knife.
60. When an iron nail is dipped in a blue copper sulphate solution, the colour of the solution changes to:
(a) Colourless
(b) Red
(c) Light green
(d) Yellow
Answer:
(c) Light green
Explanation:
Iron is more reactive than copper, so it displaces copper from the copper sulphate solution, forming iron(II) sulphate (), which turns the solution a pale/light green color.
