You visited us 1 times! Enjoying our articles? Unlock Full Access!

Byju's Answer

Standard VII

Chemistry

Mass Number

Answer the fo...

Question

Answer the following questions in one word or one sentence. [3 marks]

Name an isotope that is used in the treatment of cancer.

There are 14 protons and 13 neutrons in the nucleus of an atom. What is its mass number?

What is the charge of anode rays?

How many electrons are present in M-shell of an element having atomic number 20?

What is the valency of an atom having 3 protons and 4 neutrons.

Name any one nuclear fuel.

Open in App

Solution

Cobalt-60 [0.5 mark]

Mass number = 13 + 14 = 27 [0.5 mark]

Positive [0.5 mark]

2, 8, 8, 2 (M-shell = 8 electrons) [0.5 mark]

No. of protons = Atomic number = 3, Electronic configuration is 2, 1 and so valency is 1. [0.5 mark]

Uranium - 235 [0.5 mark]

Suggest Corrections

Similar questions

Fill in the blanks in the following statements :

(a) The number of protons in the nucleus of an atom is called its ....................

(b) The total number of protons and neutrons in the nucleus of an atom is called its ....................

(d) An atom of an element has 11 protons, 11 electrons and 12 neutrons. The atomic mass of the atom is ....................

(e) If the nucleus of an atom has atomic number 17, mass number 37 and there are 17 electrons outside the nucleus, the number of neutrons in it is ....................

(f) Almost all the mass of an atom is concentrated in a small region of space called the ....................

(g) Cathode rays are a beam of fast moving ....................

(h) The anode rays obtained from hydrogen gas consist of particles called ....................

(i) The maximum number of electrons that can be accommodated in L shell are ....................

(j) The maximum number of electrons that can go into the M shell is ....................

(k) The subatomic particle not present in a hydrogen atom is ....................

(l) The electron has .................... charge, the proton has .................... charge, and the neutron has .................... charge.

Name the following :

(a) The element which does not contain any neutron m its nucleus.

(b) An element having valency 'zero'.

(d) Two atoms having the same number of protons and electrons but different number of neutrons.

(e) The shell closest to the nucleus of an atom.

Multiple Choice Questions

(a) The outermost shell of an atom is known as

(i) valency

(ii) valence electrons

(iii) nucleus

(iv) valence shell

(b) The number of valence electrons present in magnesium is

(i) two

(ii) three

(iii) four

(iv) five

(i) proton

(ii) neutron

(iii) electron

(iv) nucleon

(d) If the atomic number of an atom is 17 and mass number is 35 then number of neutrons will be

(i) 35

(ii) 17

(iii) 18

(iv) 52

(e) The number of electrons in an atom is equal to the number of

(i) protons in a neutral atom

(ii) neutrons in a neutral atom

(iii) nucleons in a neutral atom

(iv) none of the above

(f) The sum of number of protons and number of neutrons present in the nucleus of an atom is called its

(i) mass number

(ii) atomic number

(iii) number of electrons

(iv) all of the above

The atom of an element is made up of 4 protons, 5 neutrons and 4 electrons. What are its atomic number and mass number ?

Q. An ion has 3 unit positive charge, its mass numbers is

27

and atomic number is 13. How many electrons, neutrons and protons are there in the ion?

Join BYJU'S Learning Program

Cobalt-60 [0.5 mark] Mass number = 13 + 14 = 27 [0.5 mark] Positive [0.5 mark] 2, 8, 8, 2 (M-shell = 8 electrons) [0.5 mark] No. of protons = Atomic number = 3, Electronic configuration is 2, 1 and so valency is 1. [0.5 mark] Uranium - 235 [0.5 mark]

Cobalt-60 [0.5 mark]

Mass number = 13 + 14 = 27 [0.5 mark]

Positive [0.5 mark]

2, 8, 8, 2 (M-shell = 8 electrons) [0.5 mark]

No. of protons = Atomic number = 3, Electronic configuration is 2, 1 and so valency is 1. [0.5 mark]

Uranium - 235 [0.5 mark]