Answer:
B. Na and Li
Both are group I elements.
Answer:
1. How many ATOMS of boron are present in 2.20 moles of boron trifluoride? atoms of boron.
2. How many MOLES of fluorine are present in of boron trifluoride? moles of fluorine.
Explanation:
The molecular formula of boron trifluoride is
.
So, one mole of boron trifluoride has one mole of boron atoms.
1. The number of boron atoms in 2.20 moles of boron trifluoride is 2.20 moles.
The number of atoms in 2.20 moles of boron is:
One mole of boron has ----
atoms.
Then, 2.20 moles of boron has
-
2. Calculate the number of moles of BF3 in 5.35*1022 molecules.

One mole of boron trifluoride has three moles of fluorine atoms.
Hence, 0.0888moles of BF3 has 3x0.0888mol of fluorine atoms.
=0.266mol of fluorine atoms.
Answer:
Q = 3937.56 J
Explanation:
Heat transferred due to change in temperature is given by :

c is the specific heat of water, c=4.18 J/g-°C
We have, m = 15 g, 
So,

Hence, 3937.56 J of heat is transferred.
Answer:
B
Explanation:
Dalton worked with mainly about the chemistry of atoms.
how do atoms combine to form various molecules.
—rather than the details of the physical, internal structure of atoms, although he never denied the possibility of atoms' having a substructure.
Answer:
Option B
Explanation:
As Brønsted-Lowry theory states, acids are the ones that can donate protons.
When a proton is donated, it is released to become medium more acidic.
HCl is a strong acid.
HCl (l) + H₂O (l) → H₃O⁺ (aq) + Cl⁻(aq)
These always reffers to strong acid where the dissociation is 100% completed.
In a weak acid, dissociation is not 100% complete, that's why we have an equilibrium.
HA (l) + H₂O (l) ⇄ H₃O⁺ (aq) + A⁻(aq) Ka