According to table i, which equation represents a change resulting in the greatest quantity of energy released?
1. 2c(s) + 2h2(g) -> c2h4(g)
2. 2c(s)+3h2(g) -> c2h6(g)
3. n2(g) +3h2(g)-> 2nh3(g)
4. n2(g)+o2(g) -> 2no(g)

3. N2(g) +3H2(g)->2NH3(g)

Explanation:

Reactions can be broadly classified as endothermic and exothermic reactions. In the former, energy or heat is absorbed by the reactants and the enthalpy change of the reaction is positive. In the later, heat is released ans the enthalpy change of the reaction is negative.

For the given reactions, the enthalpy change or ΔH values are:

1. 2C(s) + 2H2(g) -> C2H4(g)        ΔH = +52.4 kJ

2. 2C(s)+3H2(g) -> C2H6(g)         ΔH = -84 kj

3. N2(g) +3H2(g)->2NH3(g)          ΔH = -91.8 kJ

4. N2(g)+O2(g) -> 2NO(g)            ΔH = +182.6 kJ

Reactions 1 and 4 are endothermic while reactions 2 and 3 are exothermic in which heat is released.

More negative the ΔH value, greater is the amount of heat released.

Thus, reaction 3, represents a change resulting in the greatest quantity of energy released

yes it is balanced

- calcium has greater affinity to bond with electron receptors than hydrogen does and hence, it has the ability to replace hydrogen in most of its compounds.

- lithium has 2 valence electrons in the product because it can make only 1 bond with hydrogen. beryllium has 4 valence electrons in the product because it can only make 2 bonds. it has fewer electrons than neon and can react with electron donors. each hydrogen has 2 valence electrons, the same as helium.

- the covalent bond formed between carbon and hydrogen is polar because carbon is more electronegative than hydrogen and it attracts the bonded electron pair closer to itself, thus giving hydrogen a partial positive charge.

- a hydrogen bond is a relatively weak bond that hydrogen atoms make with the electronegative atoms nitrogen, oxygen or fluorine.

so the best choice is a.) 2 calcium (ca) atoms