Which of the following statement$(s)$ is/are incorrect?

Use the periodic table to answer the following questions.
$(a)$ Identify an element with five electrons in the outer subshell.
$(b)$ Identify an element that would tend to lose two electrons.
$(c)$ Identify an element that would tend to gain two electrons.
$(d)$ Identify the group having metal,non-metal,liquid as well as gas at room temperature.

In a period,the first ionisation enthalpy of the element at the extreme left and the negative electron gain enthalpy of the extreme right element,except noble gases,are respectively.

How many of the following statements are correct?
$(a)$ 'He' is the second most abundant element in the universe.
$(b)$ The symbol for the element with atomic number $110$ is Ds.
$(c)$ Osmium has the highest density among all elements.
$(d)$ Francium is the most electropositive element in the periodic table.

Which of the following statements is/are wrong?

Nitrogen has positive electron gain enthalpy whereas oxygen has negative. However,oxygen has lower ionisation enthalpy than nitrogen. Explain.