Select whether there is no work done by the system, work done by the system or work done by the surroundings for each system described below: a. h2o (l) \longrightarrow⟶ h2o (g) δh = 44.0 kj/mol b. 2 no (g) + o2 (g) \longrightarrow⟶ 2 no2(g) δh = -114.1 kj/mol c. cl (g) + o3 (g) \longrightarrow⟶ clo(g) + o2(g) δh = -163 kj/mol d. caco3 (s) \longrightarrow⟶ cao (s) + co2(g) δh = 110.1 kj/mol e. 4 nh3(g) + 5 o2(g) \longrightarrow⟶ 4 no (g) + 6 h2o(l) δh = -906 kj/mol

A) work done by the system;

B) work is negligible;

C) work is negligible;

D) work done by the system;

E) work doe by the surroundigs.

Explanation:

The work is the energy that a gas gain or loses to expand or compress, respectivately. So, if the gas molecules increase, the work is done by the system, if they decrease, the work is done by the surroundigs, if they don't change, or if there is no gas in the reaction, the work is  negligible.

- 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