71. The group of metals Fe, Co, Ni may best called as
A. transition metals
B. main group metals
C. alkali metals
D. rare metals
✅ The correct answer is option A.
General Science MCQs
72. Permanent hardness of water may be removed by the addition of
A. sodium carbonate
B. alum
C. potassium permanganate
D. lime
✅ The correct answer is option A.
73. Heavy water is
A. deuterium oxide
B. PH7
C. rain water
D. tritium oxide
✅ The correct answer is option A.
74. Monazite is an ore of
A. titanium
B. zirconium
C. iron
D. thorium
✅ The correct answer is option D.
75. The hardest substance available on earth is
A. Gold
B. Iron
C. Diamond
D. Platinum
✅ The correct answer is option C.
76. Which of the following is used as a lubricant?
A. Graphite
B. Silica
C. Iron Oxide
D. Diamond
✅ The correct answer is option A.
77. The gas usually filled in the electric bulb is
A. nitrogen
B. hydrogen
C. carbon dioxide
D. oxygen
✅ The correct answer is option A.
78. Balloons are filled with
A. nitrogen
B. helium
C. oxygen
D. argon
✅ The correct answer is option B.
79. Carbon, diamond and graphite are together called
A. allotropes
B. isomers
C. isomorphs
D. isotopes
✅ The correct answer is option A.
80. Potassium Permanganate is used for purifying drinking water, because
A. it is a sterilising agent
B. it dissolves the impurities of water
C. it is a reducing agent
D. it is an oxidising agent
✅ The correct answer is option D.