At STP, one mole of any gas occupies 22.4 liters. The amount of gas here is n = 11.2 L ÷ 22.4 L/mol = 0.5 mol. Molar mass is mass per mole, so M = 44.0 g ÷ 0.5 mol = 88.0 g/mol. So the molar mass is 88.0 g/mol. (Half a mole has 44.0 g, so a full mole would weigh 88.0 g.)

Dilution lowers concentration by the same factor you increase the volume. If you dilute by a factor of four, you quadruple the total volume while the amount of solute stays the same, so the concentration becomes one quarter of the original. In math terms, C_final = C_initial / 4. That means the concentration is reduced to one-quarter of what it was. The other ideas would imply increasing the concentration, halving it, or leaving it unchanged, which isn’t what happens in this dilution.

Solubility depends on both temperature and pressure because they change the balance of interactions that hold the solute and solvent together. When you raise the temperature, you’re supplying energy to break the solute’s lattice and form new interactions with the solvent. If the dissolution process is endothermic, heating makes it more favorable, so more solute dissolves. For many solids in liquids, solubility tends to increase with temperature, though there are exceptions when dissolution is exothermic. Pressure comes into play mainly for gases dissolving in liquids. According to Henry’s law, increasing the partial pressure of a gas above a solution pushes more gas into solution, so its solubility increases. For most solids, changing pressure has little effect on how much can dissolve. Agitation and surface area affect how fast dissolution occurs but not the total amount that can dissolve at equilibrium. So the true statement is that temperature and pressure do affect solubility.

In covalent bonding, how many electron pairs are shared between two atoms directly affects bond strength and length. A double covalent bond involves two electron pairs shared between the same two atoms. This higher bond order pulls the atoms closer together, making the bond shorter and stronger than a single bond, which shares only one electron pair. A triple bond, with three shared pairs, is even stronger and shorter than a double bond, but the description in the question specifically points to two electron pairs. Ionic bonds, on the other hand, result from transfer of electrons and electrostatic attraction between ions, not shared electron pairs, so they are not covalent.