NEET Chemistry Solved Question Paper 2004

The enthalphy of elements are zero in their standard state.

$\underset{= 100}{\underset{(40 + 12 + 3 \times 16)}{{\mathrm{CaCO}}_3}}$$\stackrel{∆}{\to }$ CaO + $\underset{22.4 \mathrm{litre}}{{\mathrm{CO}}_2}$

$\because$ 100 gm of CaCO₃, on decomposition, gives 22.4 litre CO₂ at STP

$\therefore$ 20 gm of CaCO₃, on decomposition, will give

 = $\frac{22.4 \times 20}{100}$ = 4.48 litre CO₂ at STP.

From de-Broglie equation,

$$\begin{gathered} \mathrm{\lambda } = \frac{\mathrm{h}}{\mathrm{mv}} \\ \therefore \mathrm{\lambda } = \frac{6.626 \times {10}^{-34} \mathrm{Js}}{40 \times {10}^{-3} \mathrm{kg} \times 20.0 {\mathrm{ms}}^{-1}} \\ = 8.28 \times {10}^{-34} \mathrm{m} \\ = 8.28 \times {10}^{-34} \times {10}^9 \mathrm{nm} \\ = 8.28 \times {10}^{-25} \mathrm{nm} \end{gathered}$$   

Newton is not the unit of pressure. It is the unit of force. Atmosphere, torr and pascal (Pa) are the units of pressure.

1 atm = 1.01 x 10⁵ Pa

1 torr = 133.3 Pa

The azimuthal quantum number (l) determines the shape of an orbital. Fore.g.

l = 0 (spherical, s)

l = 1 ( dumb- bell, p) and so on.

Ionisation energy generally increase in a period from left to right. But due to comparatively stabler configuration of Be (1s², 2s²), it has more ionisation energy than Boron (1s², 2s², 2p¹) Hence, the correct order is : B < Be < C < N.

Ca²⁺, Cl^-, S^2- and K⁺ are isoelctronic species. In isoelectronic ions, size decrease with increasing nuclear charge. Hence, Ca²⁺ ion is the smallest among these.

For Lyman series, $\frac{1}{\mathrm{\lambda }} = \mathrm{R}\left(\frac{1}{{\displaystyle {\left(1\right)}^2}} - \frac{1}{{\mathrm{n}}^2}\right)$

Hence, for $\mathrm{\lambda }$ to be smallest, n should be greatest (i.e. $\infty$)

$$\begin{gathered} \therefore \frac{1}{{\mathrm{\lambda }}_{\min }} = 1.097 \times {10}^{-2} \\ = 1.097 \times {10}^{-2} \\ \mathrm{or} {\mathrm{\lambda }}_{\min }= \frac{1}{1.097 \times {10}^{-2}} = 91.16 \mathrm{nm} \end{gathered}$$

91.16 nm is the shortest wavelength line in the Lyman series of the hydrogen spectrum.

In 1.0024, all figures are significant.

In 1.240,the significant figures are four (zero tells about precision). Zero before a number are not significant, hence, 0.0020 has only two significant numbers (2 and 0 after 2).

H₃PO₂ or hypophosphorus acid is a monobasic acid. It gives only one type of salt e.g., NaH₂PO₂.