Ask & Answer: India's Largest Education Community

This is a Multiple Choice Questions as classified in NCERT Exemplar

Option (iv)

Actinoids possess Z=90-103

Terbium is lanthanoid.

This is a Multiple Choice Questions as classified in NCERT Exemplar

Option (ii)

All the given ions are isoelectronic species thus their radii depend upon the charge more the negative charge higher would be the atomic radii and higher the positive charge lesser would be the atomic radii.

Students need not worry about the accuracy of the MBSE HSSLC result released online. MBSE 12th result 2025 will be released after various checking process. There is very less chance for the MBSE 12th result released online to be incorrect. Students are advised to collect the mark list from the school after the MBSE 12th result is announced.

Ahmedabad Business School offers BCA and MBA as its top courses. The college offers these programmes to students at the UG and PG levels. Further, the college offers these programmes for a duration of 3 and 2 years, respectively, with a comprehensive curriculum. ABS Gujarat provides students with necessrary managerial and entrepreneurial skills to excel in the changing business environment. 

This is a Multiple Choice Questions as classified in NCERT Exemplar

Answer- (c)

Explanation- The atomic number of lithium is 3, therefore, the radius of Li+ ion in its ground state, on the basis of Bohr’s model, will be about 1/3 times to that of Bohr radius.

Therefore, the radius of lithium ion is near 53/3=18≈ pm.

This is a Short Answer Type Questions as classified in NCERT Exemplar

Explanation- Hγ in Balmer series corresponds to transition n= 5 to n= 2. So, the electron in ground state i.e., from n= 1must first be placed in state n= 5.

Energy required for the transition from n= 2 to n= 5 is given by E₁-E₅=13.6-0.54=13.06eV

Since, angular momentum is conserved,

angular momentum corresponding to Hg photon= change in angular momentum of electron

so L₅-L₂=5h-2h= 3h = 3 $\times 1.06\times {10}^{-34}$

=3.18 $\times {10}^{-34}$ kgm²/s

This is a Short Answer Type Questions as classified in NCERT Exemplar

Explanation- The frequency of any line in a series in the spectrum of hydrogen like atoms corresponding to the transition of electrons from (n+ p) level to nth level can be expressed as a difference of two terms;

From the formula we can say that v=cRZ² { $\frac{1}{({n+p)}^2}-\frac{1}{n^2}$ }

Where p =1,2,3, … R os rydberg constant

When p<

V=cRZ² { $\frac{1}{n^2}({1+\frac{p}{n})}^{-2}-\frac{1}{n^2}$ }

V=cRZ² { $\frac{1}{n^2}-\frac{2p}{n^3}-\frac{1}{n^2}\}$

By binomial theorem

V=cRZ² { $\frac{2p}{n^3}=\frac{2cR{Z}^2}{n^3}p$

Thus, the first few frequencies of light that is emitted when electrons fall to the nth level

from levels higher than n, are approximate harmonic (i.e., in the ratio 1 : 2 : 3 …) when

n >> 1 .

This is a Short Answer Type Questions as classified in NCERT Exemplar

Explanation- The electron in Hydrogen atom in ground state revolves on a circular path whose radius is equal to the Bohr radius (a_n) . Let the velocity of electron is v

∴ Number of revolutions per unit time= $\frac{2\pi a_0}{V}$

The electric current is given by i=q/t, if q charge flows in time t. Here,   q=e

The electric current is given by i= $\frac{2\pi a_0}{V}e$

This is a Short Answer Type Questions as classified in NCERT Exemplar

Explanation- For a He -nucleus with charge 2e and electrons of charge− e, the energy level in ground state is

E=-13.6Z²/n²= -54.4eV

Thus, the ground state will have two electrons each of energy E and the total ground state

energy would be   - (4×13.6)eV = -54.4eV.

Ahmedabad Business School is one of the prestigious colleges and is located in Ahmedabad, Gujarat. The college is approved by the All India Council for Technical Education (AICTE) and is affiliated with the Gujarat Technological University (GTU). Ahmedabad Business School has experienced faculty members. ABS Gujarat faculty are PhD, degree, and Diploma holders. The college faculty members have worked in top companies and organisations. Further,  Ahmedabad Business School courses are offered to students at the UG and PG levels, such as BBA, BCA,  MBA, and MCA.

BTech programme at Neelkanth Group of Institutions is a four-year undergraduate course. However, candidates applying through lateral entry, after completing a Polytechnic Diploma or BSc (PCM), can directly join in the second year, reducing the duration to three years.

Those who are not satisfied with their MBSE 12th may opt for re-evaluation. The re-evaluation process for the MBSE 12th will commence soon after declaration of result. The candidates opting for re-evaluation will have to fill-up the required application form and the prescribed fees.

This is a Short Answer Type Questions as classified in NCERT Exemplar

The electronegativity of the alkali metals decreases down the group due to the increase of the shells thus Cs (Caesium) is the least electronegative metal in the alkali metals.

The total tuition fee for the BTech programme at Neelkanth Group of Institutions ranges from INR 2.1 Lacs to INR 2.4 Lakh. This may include tuition and additional components like refundable deposits. It's advisable to check the official website for the most recent fee updates.

To be eligible for BTech courses at Neelkanth Group of Institutions, candidates must have passed Class 12 with a minimum of 50% marks in PCM (Physics, Chemistry, Mathematics). Additionally, they are required to submit a valid score from either UPTAC or JEE Main. For lateral entry into BTech (2nd year), applicants must hold a Polytechnic Diploma or BSc (PCM) with at least 60% marks.

This is a Short Answer Type Questions as classified in NCERT Exemplar

Explanation- The total energy of the electron in the stationary states of the hydrogen atom is given by E_n = - $\frac{m{e}^4}{8n^2{\epsilon }_0^2{h}^2}$

where signs are as usual and the m that occurs in the Bohr formula is the reduced mass of

electron and proton. Also, the total energy of the electron in the ground state of the

hydrogen atom is−13.6 eV. For H-atom reduced mass m_e . Whereas for positronium, the

reduced mass is m=m_e/2

Hence, the total energy of the electron in the ground state of the positronium atom is

 -13.6/2=-6.8eV

This is a Short Answer Type Questions as classified in NCERT Exemplar

The radius of Na⁺ ion is smaller than that of Na is due to the following reasons:-

(i) The effective nuclear charge of Na⁺

(ii) The disappearance of 3s orbital from its outermost shell electronic configuration.