Archives

The ratio of the radii of hydrogen atom and its nucleus is ~ 10⁵. Assuming the atom and the nucleus to be spherical, (i) What will be the ratio of their sizes? (ii) If atom is represented by planet earth ‘Re ’ = 6.4 ×10⁶ m, estimate the size of the nucleus.

Answer: Assuming the atom and the nucleus to be spherical. (i) What will be the ratio of their sizes? Atomic size is represented in terms of... View Article

Why do Helium, Neon and Argon have a zero valency?

Answer: Valency is a combining capacity of an element. As there are no free electrons in the valence shell and the elements are already in a... View Article

An element X has a mass number 4 and atomic number 2. Write the valency of this element?

Answer: Mass number = 4 Atomic number = 2 X is Helium. It has 0 valency and it will not react with any other atom because it has its outer... View Article

The electronic configuration of silicon is and that of sulphur is

Answer: The electronic configuration of silicon is 2.8.4 and that of sulphur is 2.8.6. In the periodic table, silicon (Si) is a close relative... View Article

Neon and chlorine have atomic numbers 10 and 17 respectively. Their valencies will beandrespectively.

Answer: Neon and chlorine have atomic numbers 10 and 17 respectively. Their valencies will be 0 and 1 respectively. Valency is defined as the... View Article

Isotopes have same but different.

Answer: Isotopes have the same atomic number but a different mass number. An isotope is any form of a chemical element that has the same number... View Article

Rutherford’s α-particle scattering experiment led to the discovery of the ______

Answer: Rutherford’s α-particle scattering experiment led to the discovery of the atomic nucleus. According to the Rutherford... View Article

Helium atom has 2 electrons in its valence shell but its valency is not 2, Explain

Answer: He(z = 2) = 1s2 The electronic configuration of a helium atom 1s2 and which is a noble gas contains two valence electrons. Helium has 2... View Article

Complete Table 4.1 on the basis of information available in the symbols given below (a) ³⁵ ₁₇ Cl (b) ¹² ₆ C (c) ⁸¹₃₅ Br

(a) 3517 Cl (b) 126C (c) 8135 Br Element np nn Answer: The... View Article

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?

Answer: The total number of protons in the nucleus of an atom gives us the atomic number of that atom. It is represented with the letter... View Article

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 the nucleus (d) Neils Bohr – (iv) Discovery of electrons (e) James Chadwick -(v) Atomic number (f) E. Goldstein – (vi) Neutron (g) Mosley – (vii) Canal rays

Answer: A B (a) Ernest Rutherford (iii) Concept of the nucleus (b) J.J.Thomson (iv) Discovery of electrons (c)... View Article

Calculate the number of neutrons present in the nucleus of an element³¹₁₅X which is represented as

Answer: The total number of protons in the nucleus of an atom gives us the atomic number of that atom. It is represented with the letter... View Article

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.

Answer: The statement is wrong because the number of protons can never be greater than the number of neutrons. The number of protons will always... View Article

What information do you get from the Fig. about the atomic number, mass number and valency of atoms X, Y and Z? Give your answer in a tabular form.

Answer: The total number of protons in the nucleus of an atom gives us the atomic number of that atom. It is represented with the letter... View Article

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?

Answer: The noble gas's electronic configuration is 2,8. In its outermost orbitals, it has 8 electrons. The outermost shell of element X has 6... View Article

Write down the electron distribution of chlorine atom. How many electrons are there in the L shell? (Atomic number of chlorine is 17).

Answer: The atomic number of chlorine is 17. Hence it has 2 electrons in its innermost shell, 8 electrons in its second shell and 7 electrons in... View Article

One electron is present in the outer most shell of the atom of an element X. What would be the nature and value of charge on the ion formed if this electron is removed from the outer most shell?

Answer: If an electron is removed from the outermost shell a cation will be formed and the charge of the element will be +1. When a single... View Article

M	T	W	T	F	S	S
		1	2	3	4	5
6	7	8	9	10	11	12
13	14	15	16	17	18	19
20	21	22	23	24	25	26
27	28	29	30

Archives

The ratio of the radii of hydrogen atom and its nucleus is ~ 10⁵. Assuming the atom and the nucleus to be spherical, (i) What will be the ratio of their sizes? (ii) If atom is represented by planet earth ‘Re ’ = 6.4 ×10⁶ m, estimate the size of the nucleus.

Why do Helium, Neon and Argon have a zero valency?

An element X has a mass number 4 and atomic number 2. Write the valency of this element?

The electronic configuration of silicon is and that of sulphur is

Neon and chlorine have atomic numbers 10 and 17 respectively. Their valencies will beandrespectively.

Isotopes have same but different.

Rutherford’s α-particle scattering experiment led to the discovery of the ______

Helium atom has 2 electrons in its valence shell but its valency is not 2, Explain

Complete Table 4.1 on the basis of information available in the symbols given below (a) ³⁵ ₁₇ Cl (b) ¹² ₆ C (c) ⁸¹₃₅ Br

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?

Calculate the number of neutrons present in the nucleus of an element³¹₁₅X which is represented as

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.

What information do you get from the Fig. about the atomic number, mass number and valency of atoms X, Y and Z? Give your answer in a tabular form.

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).

One electron is present in the outer most shell of the atom of an element X. What would be the nature and value of charge on the ion formed if this electron is removed from the outer most shell?

Find out the valency of the atoms represented by the Fig. (a) and (b).

Why did Rutherford select a gold foil in his α–ray scattering experiment?

Will ³⁵Cl and ³⁷Cl have different valencies? Justify your answer.

FREE TEXTBOOK SOLUTIONS