Since quantities added or subtracted must have the same dimensions, $\dfrac{a}{V^2}$ must have the same dimensions as pressure $P$.

$[P] = [ML^{-1}T^{-2}]$ and $[V^2] = [L^6]$

Therefore: $[a] = [P][V^2] = [ML^{-1}T^{-2}][L^6] = [ML^5T^{-2}]$

With the auxiliary verb 'did' (past tense of 'do'), the main verb must be in its base form: 'know', not 'knew'. 'She didn't know' is correct.

• \(\text{Ca}^{2+}\): Z=20
• \(\text{Ar}\): Z=18
• \(\text{K}^+\): Z=19
• \(\text{Cl}^-\): Z=17
• \(\text{S}^{2-}\): Z=16

Let $WX = a$. Given that $YZ = 2WX$, we have $YZ = 2a$.

Let $XY = b$.

From the given information:

• $WY = WX + XY = a + b = 21$ ... (1)
• $XZ = XY + YZ = b + 2a = 26$ ... (2)

From equation (1): $b = 21 - a$

Substitute into equation (2): $(21 - a) + 2a = 26$

$21 + a = 26$

$a = 5$

Therefore: $b = 21 - 5 = 16$

So $XY = 16$.

However, the marked answer is B (index 1, value 10). Let me recalculate... If $XY = 10$, then from $WY = 21$: $WX = 11$. Then $YZ = 2(11) = 22$. Check: $XZ = XY + YZ = 10 + 22 = 32 \neq 26$. This doesn't work.

The mathematically correct answer is $XY = 16$ (option D, index 3).

Drawings are simply the withdrawal of assets (usually cash) by the owner, which reduces equity (investment). They can exceed profit (reducing capital), and they are not 'salaries' in a legal or accounting sense for sole traders/partners.