The mass of one mole of a substance in grams is called its
- A.Kilo-gram mass
- B.Gram-mass
- C.Molar-mass
- D.All the above
Correct answer
Explanation
The correct answer is C, Molar-mass. The mass of one mole of any substance, expressed in grams, is by definition its molar mass. One mole contains the Avogadro number of particles, about 6.022 × 1023, so the molar mass links the mass we can weigh to the number of atoms or molecules present. Its unit is grams per mole (g/mol), and it is numerically equal to the atomic or molecular mass in atomic mass units. Water (H2O) has a molecular mass of 18 u, so one mole of water weighs 18 g; one mole of carbon-12 weighs exactly 12 g. Option A is wrong because a kilogram is a thousand grams and 'kilo-gram mass' is not a chemical term. Option B is wrong because 'gram-mass' is not the name given to the mass of one mole. Option D is wrong because only one of the terms is correct. Exam tip: moles = given mass ÷ molar mass; one mole holds 6.022 × 1023 particles.
Practice Questions
View allWhich one of the following is monatomic?
- A.Hydrogen
- B.Sulphur
- C.Phosphorus
- D.Helium
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A monatomic element exists as single, separate atoms. Helium is a noble gas of group 18: its only shell, the first, is full with two electrons, so a helium atom has no tendency to share or transfer electrons and does not bond even with another helium atom.
Read the full explanation →The normal systolic pressure in human beings is :
- A.80 mm of Hg
- B.100 mm of Hg
- C.120 mm of Hg
- D.140 mm of Hg
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Blood pressure is written as two numbers, and normal adult blood pressure is about 120/80 mm of mercury.
Read the full explanation →'Study of human societies and cultures from the oldest times to the present' is the work of
- A.Archaeologists
- B.Anthropologists
- C.Palaeontologists
- D.Geologists
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Read the full explanation →Which of the following catalytic systems is used for the reduction of unsaturated hydrocarbon to saturated hydrocarbon?
- A.Copper and H2
- B.Iron and H2
- C.Zinc and H2
- D.Nickel and H2
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Adding hydrogen across the double or triple bond of an alkene or alkyne turns it into a saturated alkane; this reaction is called hydrogenation and it needs a catalyst.
Read the full explanation →Which one among the following is not a plant hormone ?
- A.Gibberellins
- B.Abscisic acid
- C.Auxins
- D.Thyroxine
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Thyroxine is an animal hormone, made by the thyroid gland in the neck, and it controls the rate of metabolism in the human body.
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