First one - Mg(OH)2+2HCl— MgCl2+ 2H2O
second one - CH4+2O2– 2H20
Third- is already balanced.
Assume 1 tsp is approximately can hold 5 mL liquid.
Given the dose of medicine = 1.5 tsp
Converting 1.5 tsp to mL:
= 7.5 mL
Given the specific gravity of the medicine = 1.23
That means density of the medicine with respect to water will be 1.23
As the density of water is 1 g/mL
We can take density of the medicine to be 1.23 g/mL
Calculating the mass of medicine in grams:

9.225 g medicine is present in one dose.
Explanation:
South America land mass serves as a deflector for the South equatorial current. This deflection the current causes them to move in a different direction. If the Continent were not present the direction of the South equatorial current would not change and it would continue to flow in the west.