List of top Questions asked in JEE Main, KCET

Select the plant species, where emasculation is not required for artificial hybridisation experiment.

In apple, the chromosome number of gametes is 17. What is the chromosome number in its Primary Endosperm Nucleus (PEN)?

Which pair of the following cells in the embryo sac are destined to change their ploidy after fertilization?

The genotype of a husband and wife are $I^A I^B$ and $I^A I^O$. Among the blood types of their children, how many different genotypes and phenotypes are possible?

In dihybrid cross, when \(F_1\) plants (Rr Yy) are self hybridized, the ratio of segregation of yellow and green in \(F_2\) is

In a dithecous anther, each pollen sac contains 1000 MMC. What is the total number of pollen grains produced by the anther?

Find the correct statement.
(1) Generally, a gene regulates a trait but sometimes one gene has effect on multiple traits.
(2) The trait AB-blood group of man is regulated by one dominant allele and another recessive allele. Hence it is co-dominant.

The gene for haemophilia is located on 'x' chromosome. Hence it is normally impossible for a:

If a colour-blind female marries a man whose mother was also colour blind, what are the chances of her progeny having colour blindness?

The maximum rated power of the LED is $2 \text{ mW}$ and it is used in the circuit with input voltage of $5 \text{ V}$ as shown in the figure below. The current through resistance $R$ is $0.5 \text{ mA}$. The minimum value of the resistance $R_s$, to ensure that the LED is not damaged is ______ $\text{k}\Omega$.

In the provided circuit, the input voltage is $5 \text{ V}$, a series resistor $R_s$ is connected, and the circuit then branches into two parallel paths: one with a resistor $R = 1 \text{ k}\Omega$ in series with a Zener diode, and another with the LED.

The conductivity of centimolar solution of KCl at 298 K is 0.021 $\Omega^{-1}$ cm$^{-1}$. The resistance of the cell containing the solution at 298 K is 60 $\Omega$. The value of cell constant is

$\Lambda^\circ_m (NH_4OH)$ is equal to ___________

During the electrolysis of acidified water, 16 g of O$_2$ gas is formed. The volume of H$_2$ gas liberated at cathode under STP conditions is

The activation energy for the reaction X \(\rightarrow\) Y is 150 kJ mol\(^{-1}\). The change in enthalpy for the above reaction is -135 kJ mol\(^{-1}\). Then the activation energy for Y \(\rightarrow\) X is _________.

For a reaction having three steps, the overall rate constant is \( K = \frac{k_1 k_2}{k_3} \). The values E\(_{a1}\), E\(_{a2}\) and E\(_{a3}\) (activation energies stepwise) are 40, 50 and 60 kJ mol\(^{-1}\) respectively. Then the overall E\(a\) (activation energy) of the reaction is ______

Which one of the following graph is not applicable for a 1st order reaction (R \(\rightarrow\) P)?

Given below are the half-cell reactions:
$Mn^{2+} + 2e^- \rightarrow Mn$ (E$^\circ$ = -1.18 V)
$Mn^{3+} + e^- \rightarrow Mn^{2+}$ (E$^\circ$ = +1.51 V)
The E$^\circ_{cell}$ for $3Mn^{2+} \rightarrow Mn + 2Mn^{3+}$ will be \textunderscore\textunderscore\textunderscore\textunderscore

A light wave described by E = 60[\(\sin(3 \times 10^{15})t + \sin(12 \times 10^{15})t\)] (in SI units) falls on a metal surface of work function 2.8 eV. The maximum kinetic energy of ejected photoelectron is (approximately)________ eV. (h=\(6.6 \times 10^{-34}\) J.s. and e=\(1.6 \times 10^{-19}\) C)

The pairs among $A = [SO_3^{2-}, CO_3^{2-}]$, $B = [O_2^-, F_2]$, $C = [CN^-, CO]$, $D = [NH_3, H_3O^+]$ and $E = [MnO_4^-, CrO_4^{2-}]$ that do not have similar Lewis dot structure are

In a microscope, the objective has a focal length \(f_o=2\) cm and the eye-piece has a focal length \(f_e=4\) cm. The tube length is 32 cm. The magnification produced by this microscope for normal adjustment is_____.

Given below are two statements:
Statement I: [CoBr₄]²⁻ ion will absorb light of lower energy than [CoCl₄]²⁻ ion.
Statement II: In [CoBr₄]²⁻ ion, the energy separation between the two set of d-orbitals is more than [CoCl₄]²⁻ ion.
In the light of the above statements, choose the correct answer from the options given below :

Find out the statements which are not true.
A. Resonating structures with more covalent bonds and less charge separation are more stable.
B. In electromeric effect, an unsaturated system shows +E effect with nucleophile and –E effect with electrophile.
C. Inductive effect is responsible for high melting point, boiling point and dipole moment of polar compounds.
D. The greater the number of alkyl groups attached to the doubly bonded carbon atoms, higher is the heat of hydrogenation.
E. Stability of carbanion increases with increase in s-character of the carbon carrying negative charge.

The correct order of the rate of the reaction for the following reaction with respect to nucleophiles is :
\( CH_3Br + Nu^\ominus \rightarrow CH_3Nu + Br^\ominus \)