An element X has a mass number 4 and atomic number 2. Write the valency
of this element?
. Fill in the blanks in the following statements
(a) Rutherford’s α-particle scattering experiment led to the discovery of
the ———
(b) Isotopes have same ———but different———.
(c) Neon and chlorine have atomic numbers 10 and 17 respectively. Their
valencies will be———and———respectively.
(d) The electronic configuration of silicon is ———and that of sulphur
is ———.
Helium atom has 2 electrons in its valence shell but its valency is not 2,
Explain.
The atomic number of calcium and argon are 20 and 18 respectively, but
the mass number of both these elements is 40. What is the name given to
such a pair of elements?
Match the names of the Scientists given in column A with their contributions
towards the understanding of the atomic structure as given in column B
(A) (B)
(a) Ernest Rutherford (i) Indivisibility of atoms
(b) J.J.Thomson (ii) Stationary orbits
(c) Dalton (iii) Concept of nucleus
(d) Neils Bohr (iv) Discovery of electrons
(e) James Chadwick (v) Atomic number
(f) E. Goldstein (vi) Neutron
(g) Mosley (vii) Canal rays
In response to a question, a student stated that in an atom, the number of
protons is greater than the number of neutrons, which in turn is greater
than the number of electrons. Do you agree with the statement? Justify
your answer.
In the atom of an element X, 6 electrons are present in the outermost shell.
If it acquires noble gas configuration by accepting requisite number of
electrons, then what would be the charge on the ion so formed?
Write down the electron distribution of chlorine atom. How many electrons
are there in the L shell? (Atomic number of chlorine is 17).
+91 94284 01196 (WhatsApp only)
C-15, Suvidhapark Society, Amitnagar circle, Karelibaug, Vadodara (390018)
© Copyright 2025. Doubtora. All Rights Reserved
