How many atoms are contained in 0.2moles of nitrogen? \([N_{A} = 6.02 \times 10^{23}]\)
\(1.20 \times 10^{23}\)
\(2.41 \times 10^{23}\)
\(3.62 \times 10^{23}\)
\(4.82 \times 10^{23}\)
Correct answer is A
\(1 mole = 6.02 \times 10^{23} atoms\)
\(0.2 moles = 6.02 \times 10^{23} \times 0.2\) atoms
= \(1.204 \times 10^{23}\)
\(\approxeq 1.2 \times 10^{23}\)
When chlorine is passed through a sample of water, the pH of the water sample would be
< 7
> 7
= 7
0
Correct answer is A
\(Cl_{2} + H_{2}O \to HCl + HOCl\)
The two compounds in the product end are acidic and hence, their mixture is acidic. Hence, the pH is < 7
One of the criteria for confirming the purity of benzene is to determine its
heat capacity
boiling point
mass
colour
Correct answer is B
Any pure substance will have a specific melting and boiling point. The presence of impurities alters the boiling point of benzene.
Which of the following CANNOT be an empirical formula?
\(CH\)
\(CH_{2}\)
\(P_{2}O_{5}\)
\(N_{2}O_{4}\)
Correct answer is D
The empirical formula is always in the ratio of the smallest positive integer, hence, \(N_{2}O_{4}\) has an empirical formula \(NO_{2}\)
\(Cu\) and \(HNO_{3}\) are not suitable for preparing hydrogen gas because of their
reactivity and oxidation respectively
conductivity and corrosiveness respectively
melting point and reduction respectively
electronegativity and solubility respectively
Correct answer is A
Copper is not active enough to replace hydrogen in an acid. Also, nitric acid is a strong oxidizing agent which quickly oxidises hygrogen to water.