200 cm³ of carbon (II) oxide reacts with 150 cm³ of oxygen. Calculate the volume of carbon dioxide produced and the volume of oxygen remaining.

From the equation, 2 volumes of carbon monoxide react with 1 volume of oxygen to produce 2 volumes of carbon dioxide.

Volume of $\text{O}_2$ required $= \frac{1}{2} \times \text{Volume of CO}$
Volume of $\text{O}_2$ required $= \frac{1}{2} \times 200 \text{ cm}^3 = 100 \text{ cm}^3$

Given $150 \text{ cm}^3$ of oxygen, and only $100 \text{ cm}^3$ is required, oxygen is in excess. Carbon monoxide is the limiting reactant.

Volume of $\text{O}_2$ remaining $= \text{Initial volume of O}_2 - \text{Volume of O}_2 \text{ reacted}$
Volume of $\text{O}_2$ remaining $= 150 \text{ cm}^3 - 100 \text{ cm}^3 = 50 \text{ cm}^3$

Volume of $\text{CO}_2$ produced $= \text{Volume of CO reacted}$ (due to 2:2 ratio)
Volume of $\text{CO}_2$ produced $= 200 \text{ cm}^3$

The remaining gases are carbon dioxide and oxygen.
The volume of carbon dioxide is $\boxed{\text{200 cm}^3}$.
The volume of oxygen is $\boxed{\text{50 cm}^3}$.

4. (a)
The patient should take 2 tablets, 3 times a day, for 3 days.

4. (b)
Sample 1 registered a higher temperature, meaning Flame I is hotter. A hotter flame from a Bunsen burner is produced when the air hole is fully open, resulting in a non-luminous (blue) flame.