Skip to main content

Chemistry - PYQ series 2022

 Q. The reaction of zinc with excess of aqueous alkali, evolves hydrogen gas and gives:

                                                        ( JEE mains 2022)

1. Zn(OH)2 


2.  ZnO


3. [Zn(OH)4]²-


4.  [ZnO2]²–

Ans :- [D]

Zinc dissolves in excess of aqueous alkali 

Zn + 2OH + 2H2O→ [Zn(OH)4]² + H₂ ↑ Tetrahydroxozincate(II) ion 

However, this reaction in NCERT is given as Zn+2NaOH → Na,ZnO, + H, ↑

 ZnO² is anhydrous form of [Zn(OH)4] 2- So in aqueous medium best answer of this question is [Zn(OH)4]²-

Labels:

Comments

Post a Comment

Popular posts from this blog

Chemistry - periodic table PYQ 2022

Q.The first ionization enthalpy of Na, Mg and Si, respectively, are: 496, 737 and 786 kJ mol¹. The first ionization enthalpy (kJ mol¹) of Al is:                                                         ( JEE mains 2022) 1. 487  2.  768 3. 577 4. 856 Show Answer Ans:- [c] I. E: Na < Al < Mg < Si  .. 496 <IE (Al) < 737  Option (C), matches the condition .  i.e IE (Al) = 577 kJmol-¹
Post a Comment
Read more

Physics - JEE mains PYQ

 Q. Position of an ant (S in metres) moving in Y-Z plane is given by S=2t²j+5k (where t is in second). The magnitude and direction of velocity of the ant at t = 1 s will be :                                                         (Jee mains- 2024) 1. 16 m/s in y-direction  2. 4 m/s in x- direction  3. 9 m/s in z- direction  4. 4 m/s in y-direction  Show Answer 4 m/s in y-direction. v=ds/dt=4t ĵ At t = 1 sec v = 4ĵ More Questions kinametics PYQ
Post a Comment
Read more

Chemistry - metallurgy PYQ 2022

 Q. In metallurgy the term "gangue" is used for:                                                         ( JEE mains 2022 ) 1. Contamination of undesired earthy materials. 2. Contamination of metals, other than desired metal 3. Minerals which are naturally occuring in pure form 4.Magnetic impurities in an ore. Show Answer Ans:- [A] Earthy and undesired materials present in the ore, other then the desired metal, is known as gangue.
Post a Comment
Read more

Physics - simple harmonic motion pyq 2023

 Q. In a linear simple harmonic motion (SHM) (A) Restoring force is directly proportional to the displacement.  (B) The acceleration and displacement are opposite in direction.  (C) The velocity is maximum at mean position. (D) The acceleration is minimum at extreme points.  Choose the correct answer from the options given below:                                                         (JEE mains 2023) 1. (A), (B) and (C) only   2. (C) and (D) only 3. (A), (B) and (D) only 4. (A), (C) and (D) only Show Answer Ans. (1)   F=-kx,          A true  a=-w²x.      B true  Velocity is maximum at mean position, C true  Acceleration is maximum at extreme point, D false
Post a Comment
Read more

Physics - waves PYQ series 2023

 Q. The height of transmitting antenna is 180 m and the height of the receiving antenna is 245 m. The maximum distance between them for satisfactory communication in line of sight will be :                                                         ( JEE mains 2023) 1. 48 km 2. 56 km 3. 96 km 4. 104 km Ans. (4)   dmax = √(2Rh, +2Rh) = √2x64×105×180+2×64×105×245  = {(8× 6 × 10³) + (8 × 7 × 10³)} m  = (48 +56) km  = 104 km
Post a Comment
Read more

Physics - Radioactivity PYQ 2023

 Q. The half-life of a radioactive nucleus is 5 years, The fraction of the original sample that would decay in 15 years is :                                                         ( JEE mains 2023) 1. 1/8 2. 1/4 3. 7/8 4. 3/4 Show Answer Ans. (3)  15 year = 3 half lives  Number of active nuclei = N/8  Number of decay = 7/8N
Post a Comment
Read more

Chemistry - jee mains PYQ 2023

   Q. The volume (in mL) of 0.1 M AgNO3 required for complete precipitation of chloride ions present in 20 mL of 0.01 M solution of [Cr(H2O)5Cl]Cl2 as silver chloride is                                                     (jee2023) Show Answer And: 4
Post a Comment
Read more

Chemistry PYQ - Question no. 6

 Q. Which structure of protein remains intact after coagulation of egg white on boiling?                                                         (JEE mains 2024) 1. Primary 2. Tertiary 3. Secondary 4.Quaternary Show Answer (1)  Boiling an egg causes denaturation of its protein resulting in loss of its quaternary, tertiary and secondary structures. Loading…
Post a Comment
Read more

Indefinite Integration: Complete Notes for JEE Mains & Advanced

Indefinite Integration: Comprehensive Notes for JEE Mains & Advanced Indefinite Integration is a cornerstone of Calculus, critical for JEE aspirants. It involves determining the original function when its derivative is known. This guide covers every concept, formula, and technique from basic to advanced levels, along with JEE-specific tips and tricks to solve problems faster. Table of Contents Definition Basic Formulas Advanced Forms (JEE Advanced Syllabus) Methods of Integration Special Integrals Tricks and Shortcuts Solved Examples Practice Problems Preparation Tips for JEE 1. Definition of Indefinite Integration Indefinite Integration refers to finding a function F(x) such that: \frac{d}{dx}F(x) = f(x) The integral is represented as: \int f(x) \, dx = F(x) + C where C is the constant of integration. Key I...
Post a Comment
Read more

NEET - physics 2024

 Q. A tightly wound 100 turns coil of radius 10 cm carries a current of 7 A. The magnitude of the magnetic field at the centre of the coil is (Take permeability of free space as 4π × 10–⁷ SI units)                                                         (NEET-2024) 1. 44 mT (2)  (3)  (4)  2. 4.4 T 3. 4.4 mT 4.None of these  Show Answer.   
Post a Comment
Read more