The metal purified by Mond process is X. The number of unpaired electrons in X is

${\mathrm{H}}_3{\mathrm{BO}}_3$ or $\mathrm{B}(\mathrm{OH}{)}_3$ is considered as an acid because its molecule

Identify incorrectly matched set from the following

\(20 \mathrm{~mL}\) of gas \(A\) and \(10 \mathrm{~mL}\) of gas \(B\) diffuses through a porous membrane separately in 1 minute. If the vapour density of \(B\) is \(X\), what is the vapour density of \(A\) ?

The wavelength of a spectral line emitted by hydrogen atom in the Lyman series is \(\frac{16}{15 R} \mathrm{~cm}\).
What is the value of \(n_2 ? \quad(R=\) Rydberg constant)

What are A and B in the following reactions?
\(\mathrm{A} \xrightarrow{\mathrm{H}_2 / \mathrm{Ni}} \mathrm{RCH}_2 \mathrm{NH}_2 \xrightarrow[\text { ii) } \mathrm{H}_2 \mathrm{O}] {i) \mathrm{LiA} / \mathrm{H}_4} \mathrm{~B}\)

If \(v_0\) is the threshold frequency of a metal X , the correct relation between de Broglie wavelength \((\lambda)\) associated with photoelectron and frequency \((v)\) of the incident radiation is

If the radius of electron orbit in the excited state of hydrogen atom is \(476.1 \mathrm{pm}\), the energy of electron in that excited state in \(\mathrm{J}\) is (Radius and energy of electron in the first orbit of hydrogen atom are \(52.9 \mathrm{pm}\) and \(-2.18 \times 10^{-18} \mathrm{~J}\) respectively)

The standard reduction potentials of \(\mathrm{Zn}^{2+}\left|\mathrm{Zn}, \mathrm{Cu}^{2+}\right| \mathrm{Cu}\) and \(\mathrm{Ag}^{+} \mid \mathrm{Cu}\) and \(\mathrm{Ag}^{+} \mid \mathrm{Ag}\) are respectively \(-0.76,0.34\) and \(0.8 \mathrm{~V}\). The following cells were constructed :
(1) \(\mathrm{Zn}\left|\mathrm{Zn}^{2+}\right|\left|\mathrm{Cu}^{2+}\right| \mathrm{Cu}\)
(2) \(\mathrm{Zn}\left|\mathrm{Zn}^{2+}\right|\left|\mathrm{Ag}^{+}\right| \mathrm{Ag}\)
(3) \(\mathrm{Cu}\left|\mathrm{Cu}^{2+} \| \mathrm{Ag}^{+}\right| \mathrm{Ag}\)
What is the correct order of \(E_{\text {cell }}^{\circ}\) of these cells?

Two toroids with number of turns 400 and 200 have arrange radii respectively 30 cm and 60 cm . If they carry the same current, the ratio of magnetic fields in these two toroids is

In \(\triangle A B C\), if \(\mathrm{A}\) is \((1,2), \mathrm{B}\) and \(\mathrm{C}\) lie on \(\mathrm{y}=\mathrm{x}+\alpha\) (where \(\alpha\) is variable), then the locus of the orthocenter of the triangle is

Electrons with a kinetic energy of \(6.023 \times 10^4 \mathrm{~J} / \mathrm{mol}\) are evolved from the surface of a metal, when it is exposed to radiation of wavelength of \(600 \mathrm{~nm}\). The minimum amount of energy required to remove an electron from the metal atom is

Which of the following when added to 20 mL of a 0.01 M solution of HCl would decrease its pH ?