Exercise 1

### How many neutrons and protons are there in the following nuclei?

Ans:  24 is the mass number. The number of protons in an atom equals the number of atoms in the atom. Mass number – Atomic number = 24 – 12 = 12 neutrons Numerical value of mass nubmer = 56 Number...

### How many neutrons and protons are there in the following nuclei?

Ans:  Carbon-13 mass number = 13 Carbon atomic number = number of protons in a single carbon atom = 6 As a result, the total number of neutrons in a carbon atom is calculated as follows: mass number...

### (i) Calculate the total number of electrons present in one mole of methane. (ii) Find (a) the total number and (b) the total mass of neutrons in 7 mg of 14C. (Assume that mass of a neutron = 1.675 × 10–27 kg). (iii) Find (a) the total number and (b) the total mass of protons in 34 mg of NH3 at STP. Will the answer change if the temperature and pressure are changed?

Ans: (i) 1 molecule of methane contains 10 electrons (6 from carbon, 4 from hydrogen) Therefore, 1 mole of methane contains 10*NA = 6.022*1024 electrons. (ii) Number of neutrons in 14g (1 mol)...

### (i) Calculate the number of electrons which will together weigh one gram. (ii) Calculate the mass and charge of one mole of electrons.

Ans: 1 electron weighs 9.109*10-31 kg. Therefore, number of electrons that weigh 1 g (10-3 kg) = 10-3kg/9.109*10-31 kg = 1.098*1027 electrons (ii) Mass of one mole of electrons = NA* mass of one...

### Assertion (A): It is impossible to determine the exact position and exact the momentum of an electron simultaneously. Reason (R): The path of an electron in an atom is clearly defined.

(i) Both A and R are true and R is the correct explanation of A. (ii) Both A and R are true and R is not the correct explanation of A. (iii) A is true and R is false. (iv) Both A and R are false....

### Assertion (A): All isotopes of a given element show the same type of chemical behaviour. Reason (R): The chemical properties of an atom are controlled by the number of electrons in the atom.

(i) Both A and R are true and R is the correct explanation of A. (ii) Both A and R are true but R is not the correct explanation of A. (iii) A is true but R is false. (iv) Both A and R are false....

### Match species are given in Column 1 with the electronic configuration given in Column 2.

Column 1 Column 2 (i) Cr   (a) [Ar]3d84s0   (ii) Fe2+   (b) [Ar]3d104s1   (iii) Ni2+   (c) [Ar]3d64s0   (iv) Cu   (d) [Ar] 3d54s1     (e) [Ar]3d64s2     Column 1 Column 2 (i) Cr    (d) [Ar]...

### Match the following

Column 1 Column 2 (i) Photon (a)Value is 4 for N shell (ii) Electron (b)Probability density (iii) ψ2 (c)Always a positive value (iv) The principal quantum number n   (d)Exhibits both momentum...

### Match the following

Column 1 Column 2 (i) X-rays (a) ν = 100-0 104 Hz (ii) UV (b) ν = 1010Hz (iii) Long radio waves (c) ν = 1016 Hz (iv) Microwave (d) ν = 1018Hz   Column 1 Column 2 (i) X-rays (d) ν = 1018Hz (ii) UV...

### Match the following

Rule Principle (i) Hund’s Rule   (a) No two electrons in an atom can have the same set of four quantum numbers. (ii) Aufbau Principle   (b) Half-filled and filled orbitals have extra stability....

### Match the quantum numbers with the information provided by these Quantum number Information provided

Column 1 Column 2 (i) Principal quantum number (a) orientation of the orbital (ii) Azimuthal quantum number (b) energy and size of orbital (iii) Magnetic quantum number (c) spin of an electron (iv)...

### Match the following species with their corresponding ground state electronic configuration.

Atom / Ion Electronic configuration (i) Cu (a) 1s2 2s2 2p6 3s2 3p6 3d10 (ii) Cu2+ (b) 1s2 2s2 2p6 3s2 3p6 (iii) Zn2+ (c) 1s2 2s2 2p6 3s2 3p6 3d10 4s1 (iv) Cr3+ (d) 1s2 2s2 2p6 3s2 3p63d9   (e) 1s2...

### The hydrogen atom has only one electron, so mutual repulsion between electrons is absent. However, in multielectron atoms mutual repulsion between the electrons is significant. How does this affect the energy of an electron in the orbitals of the same principal quantum number in multielectron atoms?

Hydrogen atom has only one electron, so the mutual repulsion between the electrons is non-existent. However, in multielectron atoms the interaction between electrons is important. This is because,...

### A hypothetical electromagnetic wave is shown in Figure. Find out the wavelength of the radiation.

Distance between the two identical successive points in a wave is called the wavelength. Given, In the hypothetical wave, Wavelength, λ = 4 × 2.16 pm Hence, Wavelength, λ = 8.64 pm.

### Chlorine exists in two isotopic forms, Cl-37 and Cl-35 but its atomic mass is 35.5. This indicates the ratio of Cl-37 and Cl-35 is approximately

(i) 1:2 (ii) 1:1 (iii) 1:3 (iv) 3:1     Correct Answer: (iii) 1:3 Explanation: Ratio of isotope abundance of Chlorine 37 to Chlorine 35 = A1​:A2​ Ratio of isotope abundance of Chlorine 37...

### Orbital angular momentum depends on __________.

(i) l (ii) n and l (iii) n and m (iv) m and s Correct Answer: (i) l Explanation: Orbital angular momentum depends on the value of l which is referred to as the azimuthal quantum number.

### A total number of orbitals associated with the third shell will be __________.

(i) 2 (ii) 4 (iii) 9 (iv) 3     Correct Answer: (iii) 9 Explanation: The total number of orbitals in nth shell = n2 Hence, the total number of orbitals associated with the third shell will...

### The number of radial nodes for 3p orbital is __________.

(i) 3 (ii) 4 (iii) 2 (iv) 1     Correct Answer: (iv) 1 Explanation: Number of radial nodes for 3p orbital = 3−1−1 Number of radial nodes for 3p orbital = 3−2 Number of radial nodes for 3p...

### Two atoms are said to be isobars if.

(i) they have the same atomic number but a different mass number. (ii) they have the same number of electrons but a different number of neutrons. (iii) they have the same number of neutrons but a...

### Which of the following properties of an atom could be explained correctly by Thomson Model of an atom?

(i) Overall neutrality of atom. (ii) Spectra of a hydrogen atom. (iii) Position of electrons, protons and neutrons in an atom. (iv) Stability of atom.     Correct Answer: (i) Overall...

### Which of the following statements about the electron is incorrect?

(i) It is a negatively charged particle. (ii) The mass of an electron is equal to the mass of a neutron. (iii) It is a basic constituent of all atoms. (iv) It is a constituent of cathode rays....

### Which of the following statement is not correct about the characteristics of cathode rays?

(i) They start from the cathode and move towards the anode. (ii) They travel in a straight line in the absence of an external electrical or magnetic field. (iii) Characteristics of cathode rays do...

### The probability density plots of 1s and 2s orbitals are given in Figure:

The density of dots in a region represents the probability density of finding electrons in the region. Based on the above diagram which of the following statements is incorrect? (i) 1s and 2s...