# ICSE Class 10th Physics 6 – Modern Physics MCQs

#### Which is the incomplete shell in Li atom?

Correct! Wrong!

The electronic configuration of Li is 2, 1(K, L). Hence, L-shell of lithium atom is incomplete.

#### The number of protons in an atom X, with atomic number Z and mass number A are ____.

Correct! Wrong!

The numbers of protons in an atom X of atomic number Z is Z, since, the number of protons is equal to the atomic number (Z) of an atom.

#### 7N14 and 7N15 represents ____.

Correct! Wrong!

Isotopes have same atomic number but different mass number. As 7N14 and 7N15 have same atomic number, they are isotopes.

#### Which of the following element has 6 electrons in its last shell?

Correct! Wrong!

The electronic configuration of S is 2, 8, and 6. It has 6 electrons in last shell. N, B, F have 5, 3 and 7 electrons respectively in the last shell.

#### Calculate the energy required to disintegrate the nucleus of 73Li, if the binding energy per nucleon is 5.8 Mev.

Correct! Wrong!

Given nucleus, 73Li Binding energy per nucleon = 5.8 MeV The number of nucleons in the given nucleus, (A+Z) = 7 The energy required to disintegrate the nucleus is nothing but the binding energy. Thus the binding energy = Binding energy per nucleon × Number of nucleons = 5.8 × 7 = 40.6 MeV

#### The number of valence electrons in neon atom are ____.

Correct! Wrong!

In neon atom there are 8 valence electrons.

#### When a radioactive element undergoes a beta-plus decay, the atomic number of daughter nucleus ____.

Correct! Wrong!

In case beta-plus decay, a proton transforms into neutron. AZP →A(Z−1)D + e++ν Thus, the atomic number of daughter nucleus decrease by one and the mass number remains same.

#### The number of electrons in an atom is 8 and the number of protons is 7. Then the charge on an atom will be ____.

Correct! Wrong!

As the number of protons is one less than the number of electrons, the charge will be −1.

#### A radioactive element undergoes a gamma decay. Then the atomic number of the daughter nucleus____.

Correct! Wrong!

During the gamma decay, the energy of unstable radioactive nucleus emitted in the form of photons and the nucleus becomes stable. But there is no change in the atomic number and mass number of the nucleus.

#### Four atoms A, B, C and D have atomic numbers 9, 11, 13 and 15 respectively. The atom containing less than 8 electrons in the second shell is ____.

Correct! Wrong!

The atomic number of A is 9 and its configuration will be 2, 7. Second shell of A has only 7 electrons. B, C and D have three shells and hence, have 8 electrons in the second shell.

#### Isotopes are ____.

Correct! Wrong!

Isotopes are atoms of same element having same atomic number but different mass number.

#### Which of the following elements lacks M-shell?

Correct! Wrong!

Atomic number of beryllium is 4. It has only 2 electrons in K-shell and 2 in L-shell; it does not have M- shell.

#### The atomic number of an element with 1 electron in the N-shell is____.

Correct! Wrong!

The atomic number of an element with 1 electron in the N-shell is 19, since; its electronic configuration will be 2,8,8,1.

#### An isotope of ____ is used in the treatment of cancer.

Correct! Wrong!

The isotope of cobalt (Co-60) is used in the treatment of cancer.

#### The electronic configuration of oxygen atom is ____.

Correct! Wrong!

The atomic number of oxygen is 8. Therefore, the electronic configuration of oxygen atom is 2,6.

#### Which of the following atoms do not have neutrons?

Correct! Wrong!

Hydrogen atom has no neutrons. It has 1 electron and 1 proton.

#### The maximum number of electrons that can be accommodated in the innermost shell are ____.

Correct! Wrong!

The innermost shell in an atom is K-shell and it can accommodate a maximum of 2 electrons.

#### If a neutral atom has two shells completely filled up, then atomic number of the atom is ____.

Correct! Wrong!

A neutral atom with first two shells complete is 10. K + L = 2 + 8 = 10. The atomic number of the atom is 10.

#### Which of the following statement(s) is (are) correct about the nuclear force?

Correct! Wrong!

Nuclear force is short-range and strongest attractive force. The nuclear force does not depend on charge of the particles.

#### The number of electrons in the last shell of krypton are ____.

Correct! Wrong!

Krypton has 8 electrons in its last shell.

#### The number of electrons in the L-shell of sodium atom is ____.

Correct! Wrong!

In the L-shell of the sodium atom there are 8 electrons. The electronic configuration of sodium atom is 2, 8, and 1 (K, L, M).

#### The number of electrons in aluminium ion are ____.

Correct! Wrong!

Atomic number of aluminium atom is 13. Aluminium ion is formed when aluminium atom loses 3 electrons. So, total number of electrons in aluminium ion = 13 − 3 = 10.

#### Which of the following nuclei has high average binding energy and more stable?

Correct! Wrong!

If average binding energy of a nucleus is high, the nucleus is more stable. From the average binding energy curve, it is clear that the Fe-56 nucleus has high average binding energy which is equal to 8.75 MeV. Thus the Fe-56 nucleus is more stable.

#### Which of the following decay emits electromagnetic radiation?

Correct! Wrong!

In alpha decay 42 He nucleus is emitted by the parent nucleus. In beta plus decay, positron is emitted by the nucleus along with the neutrino. in beta minus decay, electron is emitted by the nucleus along with the antineutrino. In gamma decay, the unstable nucleus emits electromagnetic radiation to get the stability.

#### The electronic configuration of an element with atomic number 12 is____.

Correct! Wrong!

The electronic configuration of an element with atomic number 12 is 2, 8, and 2.

ICSE Class 10th Physics 6 - Modern Physics MCQs
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