Some Basic Concepts of Chemistry · Chemistry · NEET

The numbers 17.0145 and 21.0235 were rounded to three figures after the decimal point. The resulting numbers, respectively, are

The amount of carbon dioxide evolved upon complete combustion of $116 g$ of $n$-butane is

(Given: atomic mass in amu $\mathrm{H}=1, \mathrm{C}=12$ and $\mathrm{O}=16$ )

The number of hydrogen atoms present in 5.4 g of urea is:

(Given: Molar mass of urea : $60 \mathrm{~g} \mathrm{~mol}^{-1}$

$\mathrm{N}_{\mathrm{A}}: 6.022 \times 10^{23}$ particles $\mathrm{mol}^{-1}$ )

When $1 \mathrm{dm}^3$ of CO₂ gas is passed over hot coke the volume of gaseous mixture after complete reaction at STP becomes $1.4 \mathrm{dm}^3$. The composition of the gaseous mixture at STP is :

Among the following, choose the ones with equal number of atoms.

A. 212 g of $\mathrm{Na}_2 \mathrm{CO}_3(\mathrm{~s})$ [molar mass $=106 \mathrm{~g}$ ]

B. 248 g of $\mathrm{Na}_2 \mathrm{O}(\mathrm{s})$ [molar mass $=62 \mathrm{~g}$ ]

C. 240 g of $\mathrm{NaOH}(\mathrm{s})$ [molar mass $=40 \mathrm{~g}$ ]

D. 12 g of $\mathrm{H}_2(\mathrm{~g})$ [molar mass $=2 \mathrm{~g}$ ]

E. 220 g of $\mathrm{CO}_2(\mathrm{~g})$ [molar mass $=44 \mathrm{~g}$ ]

Choose the correct answer from the options given below:

Dalton's Atomic theory could not explain which of the following?

The amount of glucose required to prepare $$250 \mathrm{~mL}$$ of $$\frac{\mathrm{M}}{20}$$ aqueous solution is :

(Molar mass of glucose : $$180 \mathrm{~g} \mathrm{~mol}^{-1}$$)

$$1.0 \mathrm{~g}$$ of $$\mathrm{H}_2$$ has same number of molecules as in:

On complete combustion, 0.3 g of an organic compound gave 0.2 g of CO$$_2$$ and 0.1 g of H$$_2$$O. The percentage composition of carbon and hydrogen in the compound, respectively is:

1 gram of sodium hydroxide was treated with $$25 \mathrm{~mL}$$ of $$0.75 \mathrm{~M} \mathrm{~HCl}$$ solution, the mass of sodium hydroxide left unreacted is equal to

The highest number of helium atoms is in

A compound X contains $$32 \%$$ of A, $$20 \%$$ of B and remaining percentage of C. Then, the empirical formula of $$\mathrm{X}$$ is :

(Given atomic masses of A=64 ; B=40 ; C=32 u)

The density of 1 M solution of a compound 'X' is 1.25 g mL$$^{-1}$$. The correct option for the molality of solution is (Molar mass of compound X = 85 g):

The right option for the mass of $$\mathrm{CO}_{2}$$ produced by heating $$20 \mathrm{~g}$$ of $$20 \%$$ pure limestone is

(Atomic mass of $$\mathrm{Ca}=40$$ )

$$\left[\mathrm{CaCO}_{3} \stackrel{1200 \mathrm{~K}}{\longrightarrow} \mathrm{CaO}+\mathrm{CO}_{2}\right]$$

The density of the solution is 2.15 g mL^$$-$$1, then mass of 2.5 mL solution in correct significant figures is :

What fraction of Fe exists as Fe(III) in Fe_0.96O ?

(Consider Fe_0.96O to be made up of Fe(II) and Fe(III) only)

In one molal solution that contains 0.5 mole of a solute, there is

What mass of 95% pure CaCO₃ will be required to neutralise 50 mL of 0.5 M HCl solution according to the following reaction?

CaCO_3(s) + 2HCl_(aq) $$\to$$ CaCl_2(aq) + Co_2(g) + 2H₂O_(l)

[Calculate upto second place of decimal point]