Answer:
Phosphorus, chlorine and selenium.
Explanation:
If you look at a periodic table, you will notice that phosphorus, chlorine and selenium are all in groups 15-17. Elements in these groups are more likely to gain electrons then they are to lose them, thus making them more likely to form an anion.
This is because they want to fill their outer valence shell of electrons so that they can have a full octet and for groups 15-17 it’s easier to gain 1-3 electrons then it is to loose 5-7 electrons.
Answer: Option (a) is the correct answer.
Explanation:
Atomic number is the sum of only total number of protons present in an element. Whereas mass number is the sum of total number of both protons and neutrons present in an element.
For example, given atom has mass number as 15 and its atomic number is 7.
Therefore, number of neutrons present in it will be calculated as follows.
Mass number = no. of protons + no. of neutrons
15 = 7 + no. of neutrons
no. of neutrons = 15 - 7
= 8
Thus, we can conclude that the given atom contains 8 neutrons in the nucleus.
B. The Secondary side of the step down transformer.
Answer:
I think the answer is A - they used X-ray analysis.
Explanation:
Use pv=nrT
where p is the pressure,
v is the volume,
n is the number of mole (which can be equal to mass /mr),
T is the temperature in kelvin,
and r is (molar constant) = 8.31 (units)
