OCR A-Level Chemistry A: Module 3 (Periodic table and energy) overview quiz quiz

Aluminium's outer electron is in a higher-energy $3p$ sub-shell rather than the $3s$

Aluminium has a smaller nuclear charge than magnesium, so it attracts its outer electron less

Aluminium has fewer shells than magnesium

Aluminium has a half-filled sub-shell

Sodium

Silicon

Aluminium

Sulfur

It decreases, because the atoms get smaller

It stays the same all the way down, because every metal forms a $2+$ ion

It increases, because the outer electrons are lost more easily

It decreases, because ionisation energy increases

Chlorine is only oxidised

Chlorine is only reduced

Sodium changes oxidation state from $0$ to $+1$ while chlorine is unchanged

Chlorine is simultaneously oxidised (to $+1$) and reduced (to $-1$)

Carbonate ions also form a white precipitate with barium ions, giving a false positive for sulfate

Sulfate ions chemically destroy any carbonate ions present, so the carbonate test would fail afterwards

Barium nitrate reacts only with carbonate

Carbonate ions are coloured

$-83.6\ kJ\ mol^{-1}$

$-836\ kJ\ mol^{-1}$

$+836\ kJ\ mol^{-1}$

$-8.36\ kJ\ mol^{-1}$

$+103\ kJ\ mol^{-1}$

$-263\ kJ\ mol^{-1}$

$-103\ kJ\ mol^{-1}$

$+629\ kJ\ mol^{-1}$

It lowers the activation energy

It only increases the collision frequency

It increases the concentration of the reactants, so there are more particles present to collide

It greatly increases the proportion of molecules with energy at or above the activation energy

$K_c = \frac{[NH_3]^2}{[N_2][H_2]^3}$

$K_c = \frac{[N_2][H_2]^3}{[NH_3]^2}$

$K_c = \frac{[NH_3]}{[N_2][H_2]}$

$K_c = \frac{2[NH_3]}{[N_2] + 3[H_2]}$

It increases the yield

It has no effect on the position or yield; it only speeds the approach to equilibrium

It shifts the position of equilibrium to the right and so raises the equilibrium yield of product

It decreases the yield