JEE Advanced 2021 Questions
Candidates can check some of the questions asked in the JEE Advanced 2021 exam as mentioned below.
Q.1: A heavy nucleus Q of half-life 20 minutes undergoes alpha-decay with probability of 60% and beta-decay with probability of 40%. Initially, the number of Q nuclei is 1000. The number of alpha-decays of Q in the first one hour is
(A) 50
(B) 75
(C) 350
(D) 525
Q.2:
Q.3: The correct statement(s) related to colloids is(are)
(A) The process of precipitating colloidal sol by an electrolyte is called peptization.
(B) Colloidal solution freezes at higher temperature than the true solution at the same concentration.
(C) Surfactants form micelle above critical micelle concentration (CMC). CMC depends on temperature.
(D) Micelles are macromolecular colloids.
Q.4:
Q.5: The correct statement(s) related to the metal extraction processes is (are)
(A) A mixture of PbS and PbO undergoes self-reduction to produce Pb and SO2.
(B) In the extraction process of copper from copper pyrites, silica is added to produce copper silicate.
(C) Partial oxidation of sulphide ore of copper by roasting, followed by self-reduction produces blister copper.
(D) In cyanide process, zinc powder is utilized to precipitate gold from Na[Au(CN)2].
Q.6:
Q.7: The distance between two stars of masses 3MS and 6MS is 9R. Here R is the mean distance between the centers of the Earth and the Sun, and MS is the mass of the Sun. The two stars orbit around their common center of mass in circular orbits with period nT, where T is the period of Earth’s revolution around the Sun. The value of n is ___.
Q.8:
Q.9: The correct statement(s) related to oxoacids of phosphorous is(are)
(A) Upon heating, H3PO3 undergoes disproportionation reaction to produce H3PO4 and PH3.
(B) While H3PO3 can act as reducing agent, H3PO4 cannot.
(C) H3PO3 is a monobasic acid.
(D) The H atom of P–H bond in H3PO3 is not ionizable in water.
Q.10:
Q.11: A number is chosen at random from the set {1, 2, 3, … , 2000}. Let p be the probability that the chosen number is a multiple of 3 or a multiple of 7. Then the value of 500p is ___ .
