True. Ions can have a positive or negative charge.
The effective nuclear charge is an innate property of a specific element. It is the pull of force that an electron feels from the nucleus. It is related to the valence electron by the equation: Z* = Z-S, where Z* is the effective nuclear charge, Z is the atomic number and S is the shielding constant.
For the following elements in the choices, these are their values of Z*:
Aluminum - +12.591
Beryllium - +1.912
Hydrogen - +1
Carbon - +4
The effective nuclear charge of Boron is +3. Thus, the answers are Aluminum and Carbon.
<u>Answer:</u> The element represented by M is Strontium.
<u>Explanation:</u>
Let us consider the molar mass of metal be 'x'.
The molar mass of MO will be = Molar mass of oxygen + Molar mass of metal = (16 + x)g/mol
It is given in the question that 15.44% of oxygen is present in metal oxide. So, the equation becomes:

The metal atom having molar mass as 87.62/mol is Strontium.
Hence, the element represented by M is Strontium.
Answer:
Approximately
.
Explanation:
Make use of the molar mass data (
) to calculate the number of moles of molecules in that
of
:
.
Make sure that the equation for this reaction is balanced.
Coefficient of
in this equation:
.
Coefficient of
in this equation:
.
In other words, for every two moles of
that this reaction consumes, two moles of
would be produced.
Equivalently, for every mole of
that this reaction consumes, one mole of
would be produced.
Hence the ratio:
.
Apply this ratio to find the number of moles of
that this reaction would have produced:
.