Answer:
Explanation:
To find the mass percent composition of an element, divide the mass contribution of the element by the total molecular mass. This number must then be multiplied by 100% to be expressed as a percent.
The correct answer would be D: Physical properties can be observed without changing the identity of a substance
Moles = mass / molar mass
molar mass of O2 is 32
therefore moles = 72/32
= 2.25 moles
The affect of plate movement might have on the size of the ocean basin would be negative and over many millenia it will gradually decrease in size
Answer:
(c) P and Sb
Explanation:
We can determine the number of valence electrons of an element:
- If it belongs to Groups 1 and 2, the number of valence electrons is equal to the number of group and the differential electron occupies the s subshell.
- If it belongs to the groups 13-18, the number of valence electrons is equal to: "Number of group - 10" and the differential electron occupies the p subshell.
Which pair of elements have the same valence electronic configuration of np³?
(a) O and Se. NO. They belong to the group 16 and the valence electron configuration is ns² np⁴.
(b) Ge and Pb. NO. They belong to the group 14 and the valence electron configuration is ns² np².
(c) P and Sb. YES. They belong to the group 15 and the valence electron configuration is ns² np³.
(d) K and Mg. NO. They belong to the groups 1 and 2 and the valence electron configuration is ns¹ and ns².
(e) Al and Ga. NO. They belong to the group 13 and the valence electron configuration is ns² np¹.
