PLEASE HELP ME!!:((( When hydrogen chloride reacts with magnesium, magnesium chloride and hydrogen gas are formed.

If 10.1 g of magnesium react with 26.0 g of hydrogen chloride,
1-what is the limiting reagent?
2- Theoretically how much hydrogen gas can be formed?
3- How much of the excess reagent is left over after the reaction is complete?
4- If 0.35 grams of hydrogen gas are actually formed and recovered in the reaction, what is the percent yield??

The chemical composition of soil varies with depth. an article in communications in soil science and plant analysis describes chemical analyses of soil taken from a farm in western australia. fifty specimens were each taken at depths 50 and 250 cm. at a depth of 50 cm, the average no3 concentration (in mg/l) was 88.5 with a standard deviation of 49.4. at a depth of 250 cm, the average concentration was 110.6 with a standard deviation of 51.5. find a 95% confidence interval for the difference in no3 concentrations at the two depths.