Not considering the electronic spin, the degeneracy of the second excited state (n = $3$) of H atom is $9$, while the degeneracy of the second excited state of ${\mathrm{H}}^{-}$ is :

The number of $-{\mathrm{CH}}_{2-}$ (methylene) groups in the product formed from the following reaction sequence is _____ .

A student performs a titration with different burettes and finds titre values of \(25.2 \mathrm{~mL}, 25.25 \mathrm{~mL}\), and \(25.0 \mathrm{~mL}\).
The number of significant figures in the average titre value is

The compound(s) which generate(s) $N_2$ gas upon thermal decomposition below ${300}^{o}C$ is (are)

The total number of lone pairs of electrons in ${\mathrm{N}}_2{\mathrm{O}}_3$ is

Extraction for zinc from zinc blende is achieved by

One mole of an ideal gas at $300 \mathrm{K}$ in thermal contact with its surroundings expands isothermally from $1.0 \mathrm{L}$ to $2.0 \mathrm{L}$ against a constant pressure of $3.0 \mathrm{atm}$. In this process, the change in entropy of the surroundings $\left(∆{\mathrm{S}}_{\mathrm{s}\mathrm{u}\mathrm{r}\mathrm{r}}\right)$ in $\mathrm{J}\mathrm{ }{\mathrm{K}}^{-1}$ is:
$\left(1 \mathrm{L} \mathrm{atm} = 101.3 \mathrm{J}\right)$

Let $C_1$ and $C_2$ be two biased coins such that the probabilities of getting head in a single toss are $\frac{2}{3}$ and $\frac{1}{3}$, respectively. Suppose $\alpha$ is the number of heads that appear when $C_1$ is tossed twice, independently, and suppose $\beta$ is the number of heads that appear when $C_2$ is tossed twice, independently. Then the probability that the roots of the quadratic polynomial $x^2-\alpha x+\beta$ are real and equal, is

Which of the following inequalities is/are TRUE?

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Chemical reactions involve interaction of atoms and molecules. A large number of atoms/molecules (approximately \(6.023 \times 10^{23}\) ) are present in a few grams of any chemical compound varying with their atomic/molecular masses. To handle such large numbers conveniently, the mole concept was introduced. This concept has implications in diverse areas such as analytical chemistry, biochemistry, electrochemistry and radiochemistry. The following example illustrates a typical case, involving chemical/electrochemical reaction, which requires a clear understanding of the mole concept.
A \(4.0\) molar aqueous solution of \(\mathrm{NaCl}\) is prepared and \(500 \mathrm{~mL}\) of this solution is electrolysed. This leads to the evolution of chlorine gas at one of electrodes (atomic mass: \(\mathrm{Na}=23, \mathrm{Hg}=200 ; 1\) faraday \(=96500\) coulombs).
Question:
The total number of moles of chlorine gas evolved is

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The key feature of Bohr's theory of spectrum of hydrogen atom is the quantization of angular momentum when an electron is revolving around a proton. We will extend this to a general rotational motion to find quantized rotational energy of a diatomic molecule assuming it to be rigid. The rule to be applied is Bohr's quantization condition.
Question:
A diatomic molecule has moment of inertia I. By Bohr's quantization condition its rotational energy in the \(n\)th level ( \(n=0\) is not allowed) is

The heating of \(\mathrm{NH}_4 \mathrm{NO}_2\) at \(60-70^{\circ} \mathrm{C}\) and \(\mathrm{NH}_4 \mathrm{NO}_3\) at \(200-250^{\circ} \mathrm{C}\) is associated with the formation of nitrogen containing compounds \(\mathbf{X}\) and \(\mathbf{Y}\), respectively. \(\mathbf{X}\) and \(\mathbf{Y}\), respectively, are

A horizontal force$F$is applied at the centre of mass of a cylindrical object of mass$m$and radius$R$, perpendicular to its axis as shown in the figure. The coefficient of friction between the object and the ground is$\mu$. The centre of mass of the object has an acceleration$a$. The acceleration due to gravity is$g$. Given that the object rolls without slipping, which of the following statement(s) is (are) correct?