NEET Chemistry Some Basic Concepts in Chemistry MCQs

A 20 L vessel contains 0.1 mole of $O_2$ at 300 K. $O_3$ is prepared in the vessel by subjecting $O_2$ to silent electric discharge till the volume is reduced to 15 L at 300K. What is the number of moles of $O_3$ formed?

A compound containing only carbon, hydrogen, and oxygen has a molar mass of approximately 90 g/mol. Combustion analysis of 0.405 g of the compound produces 0.54 g $CO_2$ and 0.27 g $H_2O$. If the compound's empirical formula is the same as its molecular formula, what is the number of oxygen atoms in one molecule of the compound?

A 2.00 g sample of a mixture of $CaCO_3$ and $CaSO_4\cdot2H_2O$ was heated to a constant mass of 1.55 g. What percent by mass of the original sample was $CaCO_3$?

25 mL of a mixture of $NaOH$ and $Na_2CO_3$ solution requires 20 mL of 0.5 N $HCl$ using phenolphthalein as an indicator. Another 25 mL of the same mixture requires 30 mL of the same $HCl$ solution when methyl orange is used as an indicator. Calculate the ratio of normalities of $NaOH$ and $Na_2CO_3$ in the mixture.

20 mL of a solution containing a mixture of $NaOH$ and $Na_2CO_3$ requires 10 mL of 0.5 N HCl for neutralization using phenolphthalein as an indicator. A further addition of 5 mL of the same HCl is required to reach the methyl orange endpoint. Calculate the equivalent weight of the mixture.

An element X forms a chloride with the formula XCl$_3$ and another chloride with the formula XCl$_5$. 0.1 moles of XCl$_3$ requires 60 mL of 1 N NaOH for complete hydrolysis, while 0.1 moles of XCl$_5$ requires 100 mL of 1 N NaOH. What is the equivalent weight of the element X in XCl$_3$ and XCl$_5$ respectively?

A sample of hydrated copper sulfate (CuSO₄ ⋅ xH₂O) contains 0.25 moles of water. If the total mass of the hydrated salt is 62.5 g, and the anhydrous copper sulfate (CuSO₄) has a molar mass of 160 g/mol, what is the value of 'x' (the number of water molecules per formula unit)?