List of top Questions asked in WBJEE

Increasing order of the nucleophilic substitution of following compounds is

How many electrons are needed to reduce N$_2$ to NH$_3$?
The molar conductances of Ba(OH)$_2$, BaCl$_2$ and NH$_4$Cl at infinite dilution are 523.28, 280.0 and 129.8 S cm$^2$ mol$^{-1}$ respectively. The molar conductance of NH$_4$OH at infinite dilution will be
What is the four-electron reduced form of O$_2$?
Which of the following oxides is paramagnetic?
360 cm$^3$ of a hydrocarbon diffuses in 30 minutes, while under the same conditions 360 cm$^3$ of SO$_2$ gas diffuses in one hour. The molecular formula of the hydrocarbon is
How many oxygen atoms are present in 0.36 g of a drop of water at STP?
Which of the following hydrogen bonds is likely to be the weakest?

Kjeldahl's method cannot be used for the estimation of nitrogen in which compound?
 

(A)(B)(C)(D)
NH2-CH2-COOHC6H5-NH2C6H5-N=N-C6H5O2N-C6H4-NO2
In the nuclear reaction \( \mathrm{^{10}_{5}B} + \mathrm{^{4}_{2}He} \rightarrow X + \mathrm{^{1}_{0}n} \), X represents:

In the following reaction, the major product (H) is

Which one among the following compounds will most readily be dehydrated under acidic condition?
 

(A)(B)(C)(D)
CH3-CH2-CH2-OHCH3-CH(CH3)-CH2-OHCH3-CH2-CH(CH3)-OHC(CH3)(CH3)-CH2-OH
(1° alcohol)(2° alcohol)(2° alcohol)(3° alcohol)
Adiabatic free expansion of an ideal gas must be: \} \begin{tabular}{ll} (A) Isobaric & (B) Isochoric
(C) Isothermal & (D) Isoentropic
\end{tabular}
Which of the following compounds is most reactive in S$_N$1 reaction?
Equal volumes of two solutions A and B of a strong acid having pH = 6.0 and pH = 4.0 respectively are mixed together to form a new solution. The pH of the new solution will be in the range:
An LPG (Liquified Petroleum Gas) cylinder weighs 15.0 kg when empty. When full, it weighs 30.0 kg and shows a pressure of 3.0 atm. In the course of usage at 27°C, the mass of the full cylinder is reduced to 24.2 kg. The volume of the used gas in cubic metre at the normal usage condition (1 atm and 27°C) is (assume LPG to be normal butane and it behaves ideally):
If three elements A, B, C crystallize in a cubic solid lattice with B atoms at the cubic centres, C atoms at the centre of edges, and A atoms at the corners, then the formula of the compound is:
P and Q combine to form two compounds PQ2 and PQ3. If 1 g of PQ2 is dissolved in 51 g of benzene, the depression of freezing point becomes 0.8°C. On the other hand, if 1 g of PQ3 is dissolved in 51 g of benzene, the depression of freezing point becomes 0.625°C. The atomic mass of P and Q are (Kf of benzene = 5.1 K·kg/mol):

For a chemical reaction, half-life period \(t_{1/2}\) is 10 minutes. How much reactant will be left after 20 minutes if one starts with 100 moles of reactant and the order of the reaction is:

The bond order of HeH+ is:
Increasing order of solubility of AgCl in:
  • (i) H2O
  • (ii) 1M NaCl (aq)
  • (iii) 1M CaCl2 (aq)
  • (iv) 1M NaNO3 (aq)
The equation of a stationary wave along a stretched string is given by \[ y = 5 \sin \left( \frac{\pi x}{3} \right) \cos (40 \pi t) \] Additional Information Here, \(x\) and \(y\) are in cm and \(t\) in seconds. The separation between two adjacent nodes is:
If for a matrix \( A \), \( |A| = 6 \) and \( \text{adj } A = \begin{bmatrix} 1 & -2 & 4 \\ 4 & 1 & 1 \\ -1 & k & 0 \end{bmatrix} \), then \( k \) is equal to:
If the matrix \[ \begin{pmatrix} 0 & a & a\\ 2b & b & -b\\ c & -c & c \end{pmatrix} \] is orthogonal, then the values of \( a, b, c \) are:
If \( a, b, c \) are positive real numbers each distinct from unity, then the value of the determinant \[ \left| \begin{matrix} 1 & \log_a b & \log_a c \\ \log_b a & 1 & \log_b c \\ \log_c a & \log_c b & 1 \end{matrix} \right| \] is: