List of top Chemistry Questions

The reaction that takes place when Cl2 gas is passed through conc. NaOH solution is : 

What is spectrochemical series? Explain the difference between a weak field ligand and a strong field ligand.

Nitrogen atom of amino group is _______hybridised.
What are the starting materials to get $2$-methylpropene as the major product?

What are the characteristics of the transition elements and why are they called transition elements? Which of the d-block elements may not be regarded as the transition elements?

In which of the reactions given below does H2PO4- behave as an acid?(i) H3PO4+H2O→H3O++H2PO4−(ii) H2PO4−+H2O→H3O++HPO42−(iii) H2PO4−+OH−→H3PO4+O2−
When a substance A reacts with H2O, it produces a combustible gas B and solution of C in water. When another substance D reacts with this solution of C, it produces the same gas B on warming. But D can produce the same gas B on reaction with dil. H2SO4 at room temperature. A imparts golden yellow colour to Bunsen flame. A, B, C and D respectively are
Which of the following statements is/are not true for the reaction between MnO-4 and S2–?
In the titration of Fe2+ ions versus Cr2O72– ions using diphenylamine as the internal indicator, phosphoric acid is added in the solution containing Fe2+ ions. The role of phosphoric acid is to
What will happen to the volume of a bubble of air found under water in a lake, where the temperature is 15oC and the pressure is 1.5 atm, if the bubble rises to the surface where the temperature is 25oC and the pressure is 1.0 atm?
An ideal solution of two liquids A and B is placed in a cylinder containing piston. Piston is pulled out isothermally so that the volume of the liquid decreases but that of vapours increases. Negligibly small amount of liquid was left and mole fraction of A in vapour is 0.4. If P0A = 0.4 atm and P0B at the experimental temperature, which of the following is the total pressure at which the liquid is almost evaporated?
Consider the reaction:VO + Fe2O3 → FeO + V2O5Calculate the weight of FeO produced from 2 g of VO and 5.75 g of Fe2O3.[Take atomic weights of V and Fe to be 51 u and 56 u, respectively.]
Consider the following statements:1. The nuclear fuels uranium-235 and plutonium-239 are the materials from which nuclear weapons are made.2. Radioactive radon gas is a colourless gas produced from the decay of plutonium.Which of the above given statements is/are correct?
The variation of pH during the titration of 0.5 N Na2CO3 against 0.5 N HCl is shown in the following graph:
The following table indicates the colour and pH range of different indicators:
Based on the given graph and table, which of the following statements are correct?a. The first point of inflection can be detected by cresolphthalein.b. The complete neutralisation can be detected by bromothymol blue.c. The second point of inflection can be detected by bromocresol red.d. The volume of HCl required for the first point of inflection is half of the volume of HCl required for the second point of inflection.
When 0.001 M Na2SO4 solution is saturated with CaSO4, its conductivity increases from 2.6 x 10-4 S cm-1 to 7.0 x 10-4 S cm-1. If the molar conductivities of Na+ and Ca2+ respectively are 50 S cm2 mol-1 and 120 S cm2 mol-1, then the solubility product of CaSO4 is:[Assume that conductivity of water used is negligible.]

Consider a certain reaction \(A\) \(→\) \(Products\) with \(k = 2.0 \times 10^{-2 }s^{-1}\) . Calculate the concentration of A remaining after 100 s if the initial concentration of A is 1.0 mol L-1.

The total number of protons in $ 10\,g$ of calcium carbonate is $ (N_{0}=6.023\times 10^{23})$ :
Lifetimes of the molecules in the excited states are often measured by using pulsed radiation source of duration nearly in the nano-second range. If the radiation source has a duration of 2 ns and the number of photons emitted during the pulse source is 2.5 × 1015, calculate the energy of the source.
H3PO3 can be represented by structures 1 and 2 shown below. Can these two structures be taken as the canonical forms of the resonance hybrid representing H3PO3 ? If not, give reasons for the same.
H3PO3
Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A) : Experimental reaction of $CH _3 Cl$ with aniline and anhydrous $AlCl _3$ does not give $o$ and p-methylaniline.
Reason (R) : The $- NH _2$ group of aniline becomes deactivating because of salt formation with anhydrous $AlCl _3$ and hence yields $m$-methyl aniline as the product.
In the light of the above statements, choose the most appropriate answer from the options given below :

An aromatic compound ‘A’ on treatment with aqueous ammonia and heating forms compound ‘B’ which on heating with Br2 and KOH forms a compound ‘C’ of molecular formula C6H7N. Write the structures and IUPAC names of compounds A, B and C

Arrange the following: 

(i) In decreasing order of the pKb values: C2H5NH2 , C6H5NHCH3 , (C2H5 )2NH and C6H5NH2 

(ii) In increasing order of basic strength: C6H5NH2 , C6H5N(CH3 )2 , (C2H5 )2NH and CH3NH2 

(iii) In increasing order of basic strength: (a) Aniline, p-nitroaniline and p-toluidine Exercises Rationalised 2023-24 279 Amines (b) C6H5NH2 , C6H5NHCH3 , C6H5CH2NH2 . 

(iv) In decreasing order of basic strength in gas phase: C2H5NH2 , (C2H5 )2NH, (C2H5 )3N and NH3 

(v) In increasing order of boiling point: C2H5OH, (CH3 )2NH, C2H5NH2 

(vi) In increasing order of solubility in water: C6H5NH2 , (C2H5 )2NH, C2H5NH2 .

The radius of Na atom forming bcc lattice (in Å)?
Ba+2 cannot be precipitated as?
The correct increasing order of the magnitude of standard enthalpies of formation for group-1 halides is?