Wound packing with sinus tracts (tunnels) requires:

• Loose packing to fill dead space without pressure — tight packing impairs circulation and healing
• Use moistened gauze (saline-moistened) — maintains a moist wound environment that promotes healing
• Packing prevents premature surface closure while the wound heals from the base upward (primary intention vs. secondary intention healing)

Wound packing principles:

1. Measure depth and width at each dressing change
2. Document amount of packing material inserted and removed
3. Pack gently to avoid trauma
4. Do not pack so tightly that it creates pressure necrosis
5. Use sterile technique throughout

Failure to pack sinus tracts properly leads to premature wound closure with abscess formation underneath.

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

Initial vertical component: $v_y = v\sin45° = \dfrac{v}{\sqrt{2}}$ (upward)

On landing (by symmetry): $v_y' = \dfrac{v}{\sqrt{2}}$ (downward)

Horizontal component unchanged. Change in momentum:

$|\Delta\vec{p}| = m\left|\Delta v_y\right| = m\cdot\dfrac{2v}{\sqrt{2}} = \mathbf{mv\sqrt{2}}$

Option B is correct.

Unpresented cheques are written and recorded in the cash book but not yet presented to the bank — they are timing differences shown on the reconciliation.

• A: Bank charges update the cash book.
• C: Credit transfers update the cash book.
• D: Cash book errors are corrected in the cash book.

Lassaigne's test is used to detect Nitrogen, Halogens, and Sulfur. However, the compound must contain Carbon and Nitrogen (to form $CN^-$) or a Halogen (to form $X^-$) to give a positive result with $AgNO_3$.

• Aniline ($C_{6}H_{5}NH_{2}$) contains nitrogen, which forms $NaCN$. When reacted with $AgNO_3$, it doesn't give a halide precipitate like the other options which contain chlorine [cite: 3, 4].
• $C_{6}H_{5}Cl$, $CH_{3}Cl$, and $CH_{2}Cl_{2}$ all contain Chlorine and will form a white precipitate of $AgCl$[cite: 25, 26].