It is equal to maximum potential difference when no current is drawn from the cell.

\(\begin{gathered} \mathrm{Zn}(s)+\mathrm{NO}_{3}^{-}(a q) \longrightarrow \mathrm{Zn}^{2+}(a q)+\mathrm{NH}_{4}^{+}(a q)+\mathrm{H}^{+} \text {(Acidic medium) } \\ {\left[\mathrm{Zn} \longrightarrow \mathrm{Zn}^{2+}+2 \mathrm{e}^{-} \ldots(i)\right] \times 4} \\ 10 \mathrm{H}^{+}+8 \mathrm{e}^{-}+\mathrm{NO}_{3}^{-}(a q) \longrightarrow \mathrm{NH}_{4}^{+}(a q)+3 \mathrm{H}_{2} \mathrm{O} \ldots(\mathrm{ii}) \\ +5 \quad-3 \\ \hline 4 \mathrm{Zn}+10 \mathrm{H}^{+}+\mathrm{NO}_{3}^{-} \longrightarrow 4 \mathrm{Zn}^{2+}+\mathrm{NH}_{4}^{+}+3 \mathrm{H}_{2} \mathrm{O} \\ \hline \end{gathered}\)

According to Rydberg-Balmer equation.
\(\frac { 1 }{ \lambda } =R\left[ \frac { 1 }{ n^{ 2 }_{ 1 } } -\frac { 1 }{ n^{ 2 }_{ 2 } } \right] =R\left[ \frac { 1 }{ 1^{ 2 } } -\frac { 1 }{ n^{ 2 }_{ 2 } } \right] \)
The wavelength (\(\lambda \))will be the longest when n₂ is the smallest i.e., n₂ = 2 and 3 for two longest wavelength lines.
For n₂ = 2 : \(\frac { 1 }{ \lambda } \)= (1.097 x 10^-2 nm^-1)\(\left[ \frac { 1 }{ 1^{ 2 } } -\frac { 1 }{ 2^{ 2 } } \right] \)
= (1.097 x 10^-2 nm^-1) x 4 = 8.228 x 10^-3 nm^-1 or \(\lambda \).= 121.54 nm
For n₂ = 3 : \(\frac { 1 }{ \lambda } \)= (1 097 x 10^-2 nm^-1)\(\left[ \frac { 1 }{ 1^{ 2 } } -\frac { 1 }{ 3^{ 2 } } \right] \)
= (1.097 x 10^-2 nm^-1) x (8/9) = 9.75 x 10^-3 nm^-1 ; \(\lambda \).= 102.56 nm

Step I. Calculation of the velocity of electron
Kinetic energy = 1/2 mv² = 4.55 x 10^-25J = 4.55 x 10^-25 kg m² S^-2
or v² = \(\frac { 2\times KE }{ m } =\frac { 2\times (4.55\times10^{ -25 }kgm^{ 2 }s^{ -2 }) }{ (3x10^{ 6 }ms^{ -1 }) } \)=10⁶ m² S^-2
or Velocity (v) = (10⁶ m² S^-2 )^1/2 = 10³ ms^-1
Step II. Calculation of the momentum of the electron Momentum of electron = mv = (9.1 x 10^-31 kg) x (10³m s^-l) = 9.1 x 10^-28 kg m^-1
Step III. Calculation of the wavelength of the electron According to de Broglie equation:
\(\lambda \frac { h }{ mv } =\frac { (6.626\times10^{ -34 }kgm^{ 2 }s^{ -1 }) }{ (9.1x10^{ -31 }kg)\times (10^{ 3 }ms^{ -l }) } \)
= 0.728 x 10-6m = 7.28 x 10-7 m

As shown in figure, the masses of H and O which combine with the fixed mass of S, i.e. 32 parts are 2 and 32 i.e. they are in the ration 2: 32 or 1:16. When H and O combine directly to form H₂O, the ratio of their combining, masses are 2:16 or 1:8.
combine directly to form H₂O, the ratio of their combining, masses are 2:16 or 1:8.
These ratio are related to each other as \(\frac { 1 }{ 16 } :\frac { 1 }{ 8 } =1:2\) 
i.e. they are simple multiple of each other.

mass of \({ O }_{ 2\\ }\)molecule = \(=5.32\times { 10 }^{ -23 }g\) ;
mass of \({ SO }_{ 2 }\) molecule \(=1.06\times { 10 }^{ -22 }g\)

Fe is more reactive than hydrogen, it has lower reduction potential than hydrogen whereas Cu has higher reduction potential than hydrogen, copper cannot displace hydrogen from steam because it is less reactive than hydrogen.

1s²2s²2p⁶3s²3p⁶4s⁰3d⁸. [∴ Electrons are removed from 4s orbital first, then from 3d].

In the construction of electron microscope used for the measurement of objects of very small size.

This is due to the presence of dust particles.

Suppose that the oxidation number of P in \({ HPO }_{ 3 }^{ 2- }\) be x.
Theb, 1 + x + 3 (-2) = -2
or x + 1 - 6 = -2 or x = +3

The given equation shows that 1 mole of A reacts with 1 mole of \({ B }_{ 2 }\) and 1 atom of A reacts with 1 molecule of \({ B }_{ 2 }\).
2.5 moles of B will react with 2.5 moles of A, hence Bb is the limiting reagent.

Wavelength is the distance between two successive crests or two successive troughs of a wave.
There, \(\lambda =4\times 2.16pm=8.64 \ pm \)

HCI is neutralised by AI(OH)₃ by equation,
\(Al{ (OH) }_{ 3 }+3HCl\longrightarrow AlC{ l }_{ 3 }+3{ H }_{ 2 }O\)
HCI produced from 2.5 L of gastric juice
\(=3\times { 10 }^{ -3 }\times { 10 }^{ 3 }\times 2.5\)
109.5g HCl is neutralised by Al(OH)₃ = 78 g
7.5 g HCl is neutralised by Al(OH)₃\(=\frac { 78 }{ 109.5 } \times 7.5\quad 3g\)
Number of tablets required \(=\frac { 5.342 }{ 0.4 } =13.35=14\) tablets

(d) Assertion is incorrect, reason is correct.