When hydrogen is burned in the presence of oxygen it will form water, as per the equation: 2H2 + O2 -> 2H2O. Which types of reactions does this fall under? I. synthesis
II. decomposition
III. single replacement
IV. double replacement
V. combustion

A. I, II, and III
B. I and V
C. II, III, and IV
D. II and IV

B

Explanation:

Hydrogen is synthesized to water by adding Oxygen.

Hydrogen is oxidised to water by combustion ( burning in presence of oxygen).

what is the question?

the seeing the electronic configuration we can say that the element is fluorine.

fluorine is the most electronegative element in the periodic table.

but by only seeing the configuration we cannot say about its reactivity because we don't know if its configuration after excitation or by addition of electrons.

but if not then, it is the lightest halogen and exists as a highly toxic pale yellow diatomic gas at standard conditions. as the most electronegative element, it is extremely reactive: almost all other elements, including some noble gases, form compounds with fluorine.