Chemistry Test - 16

Number of atoms in \(20 \mathrm{~g}\) \(\mathrm{Ca}=\frac{\text { weight }}{\text { Atomic weight }} \times \mathrm{N}_{\mathrm{A}}\)

\(=\frac{20}{40} \times 6.023 \times 10^{23}\)\(=3.0115 \times 10^{23}\) atoms

(A) Number of atoms in \(24 \mathrm{~g}\) \(\mathrm{Mg}=\frac{24}{24} \times 6.023 \times 10^{23}=6.023 \times 10^{23}\) atoms

(B) Number of atoms in \(8 \mathrm{~g}\) Oxygen \(=\frac{8}{16} \times 6.023 \times 10^{23}=3.0115\) \(\times 10^{23}\) atoms

(C) Number of atoms in \(12 \mathrm{~g}\) Carbon \(=\frac{12}{12} \times 6.023 \times 10^{23}=6.023\)\(\times 10^{23}\) atoms

(D) Number of atoms in \(16 \mathrm{~g}\) Oxygen \(=\frac{16}{16} \times 6.023 \times 10^{23}=6.023\)\(\times 10^{23}\) atoms

\(\mathrm{R}-\mathrm{CH}=\mathrm{CH}_{2} \stackrel{\mathrm{B}_{2} \mathrm{H}_{5}}{\longrightarrow}\left(\mathrm{R}-\mathrm{CH}_{2}-\mathrm{CH}_{2}\right)_{3}-\mathrm{B} \stackrel{\mathrm{OH}^{-}}{\longrightarrow} \mathrm{R}-\mathrm{CH}_{2}-\mathrm{CH}_{2} \mathrm{OH}\)

Hydroboration of alkanes followed by hydrolysis in basic medium yield alcohols and not the alkanes.

When hydrogen peroxide is added to an acidified solution of potassium dichromate, a blue colour is produced due to the formation of \(\ce{CrO5}\).

Step (i) \(\ce{K_{2} Cr_{2} O_{7} +H_{2} SO_{4}-> K_{2} SO _{4}+ H_{2} Cr_{2} O_{7}}\)

Step (ii) \(\ce{\left[ H_{2} O_{2}->H_{2}O +(O)\right]4}\)

Step (iii) \(\ce{H_{2}Cr_{2}O_{7}+4(O)->2 CrO_{5} + H_{2}O}\)

Thus, \(\ce{K_{2}Cr_{2}O_{7} + H_{2}SO_{4} + 4 H_{2} O_{2}->2CrO_{5} + K_{2}SO_{4} +5H_{2}O}\)

The formation of Chromium Pentaoxide leads to the formation of blue colour from orange (as potassium dichromate is orange in colour). Chromium Pentaoxide is blue, so we get a blue colour after the reaction.

In the reaction, Hydrogen peroxide acts as an oxidizing agent, because it gets reduced, and its oxidation number changes to \(-2\) from \(-1\)

Oxidation state of iron in \(F e(C O)_{4}\) is 0.

In the formation of metal carbonyls, two types of bond are formed. Initially, carbonyl ligand \((C O)\) donates its electron pair to the central metal atom due to which metal gets a negative charge which makes it unstable. Therefore, the metal again forms back bonding with the ligand due to which the net result is the zero charge on metal atom.

The molecules or chemicals present in the human body are known as biomolecules. They are primarily of two types - inorganic and organic. Inorganic constituents of the cellular pool are minerals, gases, and water. They do not contain carbon along with hydrogen, unlike the organic constituents.Living cell contains \(60\)-\(75\%\) water. Like hydrolases in our body, there are a set of enzymes that requires water to cleave a chemical bond. Insufficient water uptake causes dehydration and increases the chances of kidney stones.About \(65\)-\(70\%\) of the human body is composed of water which amounts to two- thirds of our body.

Given,

\(3 \mathrm{~g}\) of activated charcoal was added to \(50 \mathrm{~mL}\) of the acetic acid solution \((0.06 \mathrm{~N})\) in a flask. 

\(50 \mathrm{~mL}\) of \(0.06 \mathrm{~N}\) acetic acid solution contains \(0.06 \mathrm{~mol} / \mathrm{L}\)

\(\times \frac{50 \mathrm{~mL}}{1000 \mathrm{~mL} / \mathrm{L}} \times 60 \mathrm{~g} / \mathrm{mol}=0.180 \mathrm{~g}\) of acetic acid.

After filtration, \(50 \mathrm{~mL}\) of \(0.042 \mathrm{~N}\) acetic acid solution contains \(0.042 \mathrm{~mol} / \mathrm{L} \times \frac{50 \mathrm{~mL}}{1000 \mathrm{~mL} / \mathrm{L}}=0.126 \mathrm{~g}\) of acetic acid.

Thus, the amount of acetic acid adsorbed on \(3 \mathrm{~g}\) of activated charcoal is \(0.180 \mathrm{~g}-0.126 \mathrm{~g}=0.054 \mathrm{~g}\). This is equal to \(54 \mathrm{mg}\).

So, the amount of acetic acid adsorbed on \(1 \mathrm{~g}\) of activated charcoal is \(\frac{54 \mathrm{mg} \times 1 \mathrm{~g}}{3 \mathrm{~g}}=18 \mathrm{mg}\).

This is known as Griess-Ilosvay test.

1. \(\left[\mathrm{Fe}\left(\mathrm{H}_2 \mathrm{O}\right)_6\right]^{3+}\)

\(\mathrm{Fe}^{3+}:[\mathrm{Ar}] 3 \mathrm{~d}^5\)

Hybridisation : \(\mathrm{sp}^3 \mathrm{~d}^2\)

Magnetic nature: Paramagnetic (so this complex response to

external magnetic field)

2. \(\left[\mathrm{Ni}(\mathrm{CN})_4\right]^{2-}\)

\(\mathrm{Ni}^{2+}:[\mathrm{Ar}] 3 \mathrm{~d}^8\)

Hybridisation: dsp \({ }^2\)

Magnetic nature : diamagnetic

3. \(\left[\mathrm{Co}(\mathrm{CN})_6\right]^{3-}\)

\(\mathrm{Co}^{3+}:[\mathrm{Ar}] 3 \mathrm{~d}^6\)

Hybridisation: \(\mathrm{d}^2 \mathrm{sp}^3\)

Magnetic nature : diamagnetic

4. \(\left[\mathrm{Ni}(\mathrm{CO})_4\right]\)

\(\mathrm{Ni}:[\mathrm{Ar}] 3 \mathrm{~d}^8 4 \mathrm{~s}^2\)

Hybridisation : \(\mathrm{sp}^3\)

Magnetic nature : diamagnetic