MEDIUM
9th CBSE
IMPORTANT
Earn 100
How do you define the valency of an element in a molecular compound?
(i) It's combining capacity and is equal to the number of hydrogen atoms.
(ii) Number of chlorine atoms.
(iii) Ratio of molar should be equal.
(iv) Double the number of oxygen atoms with which one atom of the element combines.
50% studentsanswered this correctly
Important Questions on Atoms and Molecules
MEDIUM
9th CBSE
IMPORTANT
One mole of means
(i)molecules of
(ii) at STP
(iii) of
(iv) of
MEDIUM
9th CBSE
IMPORTANT
The Scientist Proust established which of the below-mentioned law in the year ?
(i) In a chemical substance its constituent elements are present in definite proportions by mass.
(ii) A pure compound has a definite composition by mass of its constituent elements.
(iii) It is not possible to create or destroy the mass of a substance by chemical reactions.
(iv) Atoms combine in whole numbers.
MEDIUM
9th CBSE
IMPORTANT
Which of the following are incorrect?
(i) Atoms are divisible particles.
(ii) Atoms can be created or destroyed during a chemical reaction and all matter is made up of atoms.
(iii) Mass of the matter is due to the mass of atoms that constitute it.
(iv) Atom and mass are not conserved.
EASY
9th CBSE
IMPORTANT
Which of the following are mono atomic metallic elements?
(i) Sodium
(ii) Copper
(iii) Aluminium
(iv) All of above.
MEDIUM
9th CBSE
IMPORTANT
Which of the following statement about polyatomic ions are correct?
(i) A group of two or more atoms carrying a charge is called a polyatomic ion.
(ii) A polyatomic cation carries a charge.
(iii) A polyatomic anion carries a negative charge.
(iv) A polyatomic cation does not carry a charge.
MEDIUM
9th CBSE
IMPORTANT
Which of the following are the correct options?
(i) Law of conservation of mass is the law of indestructibility of matter.
(ii) Atoms masses are the average relative masses of the atoms.
(iii) Atoms may or may not be capable of free existence but molecules can always exist freely.
(iv) A group of atoms carrying both the charges.
MEDIUM
9th CBSE
IMPORTANT
Which of the following support modified Dalton's Atomic theory?
(i) It is not possible to create or destroy the mass of a substance by chemical reactions.
(ii) Atoms of the same element have the same chemical properties but they may have different physical properties.
(iii) Atoms of an element have the same mass was proved wrong when it was found that an element may exist in atoms with different masses, e.g. chlorine atoms with masses and etc.
EASY
9th CBSE
IMPORTANT
Which of the following symbols of elements are incorrect?
(i) Cobalt
(ii) Aluminium
(iii) Carbon
(iv) Helium
