Chemistry

Q.

Balance the equation: $\mathrm{Ca}{\left(\mathrm{OH}\right)}_2+{\mathrm{CO}}_2\to {\mathrm{CaCO}}_3+{\mathrm{H}}_2\mathrm{O}$

Q. 32. Write balanced chemical equations of (i) Solutions of barium chloride and sodium sulphate in water react to give insoluble barium sulphate and the solution of sodium chloride. (ii) sodium hydroxide solution ( in water) reacts with hydrochloric acid solution (in water) to produce sodium chloride solution and water.

Q.

Calculate the bond order of ${\mathrm{O}}_2$.

Q. What is the relation between mole fraction and molality?

Q. Find the total number of electrons present in $1.6\text{g}$ of $C{H}_4$.

1. $6.023\times {10}^{23}$ electrons
2. $6.023\times {10}^{20}$ electrons
3. 10 electrons
4. 1 electron

Q.

What is the electron configuration of chromium?

Q. In hydrogen atom the de broglie wavelength of an electron in the second Bohr orbit is 1-105.8pm 2-211.6pm 3-211.6π pm 4-52.9π pm

Q. 26. In a cubic unit cell , A atoms are atoms are present on alternate corners, B atoms are present on alternate face centers and C atoms are present on alternative edge centers and body centers of the cube . The simplest formula of the compound is:- (1)ABCD (2)A2BC4 (3)AB2C4 (4)none

Q. From $200\text{mg}$ of $C{O}_2$, ${10}^{21}$ molecules are removed. How many moles of $C{O}_2$ are left?

1. $2.88\times {10}^{-3}\text{mol}$
2. $7\times {10}^{-2}\text{mol}$
3. $2.88\times {10}^{-1}\text{mol}$
4. $2.8\text{mol}$

Q.

Amount of water produced by the combustion of 16g of methane is:

1. 36 g

2. 34 g

3. 32 g

4. 30 g

Q. The molarity of $98\%$ $H_{2}S{O}_4$ $(d=1.8\frac{g}{ml})$ by weight is :

1. $6M$
2. $18M$
3. $10M$
4. $4M$

Q. NaCl forms an ionic crystal in which Cl- ions forms CCP lattice. The number of Na+ ions present at a distance of √5 A/2 from Cl- ion at the corner is

Q.

Calculate the bond order of $O_2^{-}$.

Q.

7. Balance the given skeleton equation:

$KMn{O}_4+HCl⟶KCl+Mn{Cl}_2+H_{2}O+{Cl}_2$

Q.

Calculate the concentration of nitric acid in moles per litre in a sample which has a density, 1.41 g mL^–1 and the mass per cent of nitric acid in it being 69%.

Q. Derive the formula : Molarity = (% by weight × 10 × d )/ GMM Here d is density and GMM is gram molecular mass .

Q. iron oxide has formula Fe0.94O. what fraction of Fe exsist as Fe3+

Q.

The number of atoms present in 120 amu of Ca are

Q. calculate the volume occupied by 28u nitrogen gas

Q.

Chlorine is prepared in the laboratory by treating manganese dioxide (MnO₂) with aqueous hydrochloric acid according to the reaction

4HCl_(aq) + MnO_2(s) → 2H₂O_(l) + MnCl_2(aq) + Cl_2(g)

How many grams of HCl react with 5.0 g of manganese dioxide?

Q.

What are stereoisomers? Give an example.

Q.

Molarity of NaOH in a solution prepared by dissolving 4 g of NaOH in enough water to form 250 ml of solution is:

1. 0.4 M

2. 4.1 M

3. 1.4 M

4. 0.45 M

Q. find the volume of O2 at STP required for the complete combustion of 4g CH4 i)5.6L ii)2.88L iii)22.4L iv)11.2

Q.

What is polarizing power and polarizability?

Q. 4. With 63 gm of oxalic acid how many litres of N/10 solution can be preoared (1) 100 litre (2) 10 litre (3) 1 litre (4) 1000 litre

Q. what is the sequence of boiling point of alcohol, aldehyde, ketone, ether, carboxylic acid, amine and amide with proper reason?

Q.

The total energy of an electron in the n^th orbit of a hydrogen atom is given by the formula E_n = -13.6 eV/n². What does the negative energy for an electron indicate?

1. Electrons have both wave and particle-like properties.

2. The electron has a negative charge.

3. The electron is far away from nucleus.

4. Energy of electron in an atom is lower than the energy of an electron far away from nucleus.

Q. $KBr$ is doped with ${10}^{-5}$ mole percent of $SrB{r}_2$. the number of cationic vacancies in $1g$ of $KBr$ crystal is${10}^{14}$. (Round off the nearest integer). [Atomic mass: $K:39.1u,Br:79.9u,N_A=6.023\times {10}^{23}$]
(JEE Main 2021)

Q. 3. calculate the mole fraction of ethanol and water in a sample of rectified spirit which contain 92% by mass

Q. 44.The vanthoff factor for a 0.1 M Al2(so4)3 solution is 4.20 .The degree of dissociation is