Q.28 Let nCrnCr denote the number n!r!(n−r)!r!(n−r)!n!. Then for n=100n=100, the sum of the series 1−nC1+nC2−nC3+⋯+(−1)rnCr+⋯+(−1)nnCn1−nC1+nC2−nC3+⋯+(−1)rnCr+⋯+(−1)nnCn is (A) 0 (B) 1 (C) 2 (D) 1024 Quick Answer The given series is an alternating binomial […]
Q.27 Three NOT gates are connected in series and the output of the last gate is fed back to the input of the first one as shown in the figure. […]
Q.26 The minimum light intensity that the human eye can perceive is 10−10 W m−210−10 W m−2. The area of opening of our eye (the pupil) is approximately 0.4 cm20.4 cm2. Consider yellow light with wavelength λ=600 nmλ=600 nm. The number […]
Q.25 An archaeological sample (remains of an animal) containing 14C14C isotope of Carbon is found to give 10 beta decays per minute per gram of Carbon. It is known that the natural […]
Q.24 The major product in the following reaction is Introduction The question shows diethyl 3‑oxoglutarate treated successively with NaOEt/EtOH, Br(CH₂)₂Br, followed by acidic hydrolysis and heating, and asks for the major […]
Q.23: Meso 2,3-Dibromobutane Synthesis Question Statement The compound meso 2,3-dibromobutane is obtained by (A) electrophilic addition of HBr to (E)-1-bromobut-2-ene (B) electrophilic addition of Br2 to (E)-2-butene (C) electrophilic addition […]
Q.22: UV Spectroscopy Transitions Analysis Question Statement The UV spectrum of 2-butanone and the UV spectrum of methyl vinyl ketone (MVK) are independently recorded and compared. Among the various λmax, […]
Q.21: Rate Constant Unit Conversion Question Statement The rate constant for the reaction O(g) + O3(g) → 2O2(g) is 8.0 × 10–15 cm3 molecule–1 s–1. The rate constant in dm3 […]
Q.20: Enzymes and Industrial Applications Matching Question Statement Which one of the following options shows the correct pairing of the enzyme with its corresponding application? P. Papain i. Gluten complex […]
![Q.19: B Cells and T Cells Immunity Assertion-Reason Question Statement Determine the correctness or otherwise of the following Assertion [a] and Reason [r]. Assertion [a]. B cells secrete antibodies against a virus while cytotoxic T cells kill virus-infected cells. Reason [r]. B cells confer active immunity while cytotoxic T cells confer passive immunity. (A) [a] and [r] are true and [r] is the correct reason for [a] (B) [a] and [r] are true but [r] is not the correct reason for [a] (C) [a] is true but [r] is false (D) [a] false but [r] is true](https://www.letstalkacademy.com/wp-content/uploads/2025/12/slide_19-12.jpg)
Q.19: B Cells and T Cells Immunity Assertion-Reason Question Statement Determine the correctness or otherwise of the following Assertion [a] and Reason [r]. Assertion [a]. B cells secrete antibodies against […]
