I don’t see what you need help with but thanks:)
Answer:
0.12 M
Explanation:
Step 1: Write the balanced equation
NaOH + HCl ⇒ NaCl + H₂O
Step 2: Calculate the reacting moles of NaOH
10 mL of a 0.30 M NaOH solution react.

Step 3: Calculate the reacting moles of HCl
The molar ratio of NaOH to HCl is 1:1. The reacting moles of HCl are 1/1 × 3.0 × 10⁻³ mol = 3.0 × 10⁻³ mol.
Step 4: Calculate the concentration of HCl
3.0 × 10⁻³ mol of HCl are in 25 mL of solution.

Answer:
Explanation:
1) Find number of each of the type of atom that is present in the compound, using the chemical formula .
2) Then multiply number of atoms of each element that is present in the compound with the atomic weight of each of the element
3) Add everything together and add the units (grams/mole ) after the number
Let finds that of water
Chemical formula of water is (H20 )
hydogens atoms= 2
oxygen atom= 1
Atomic weight for Hydrogen= 1
Atomic weight for Oxygen= 16
Total number of atoms of Hydrogen from the formula (H2O)= 2
Total number of atoms of Oxygen from the formula (H2O)= 1
the molar mass=
Hydrogen: ( 2 x 1)= 2
Oxygen: ( 1 x 16)= 16
Add together= (16+2)
= 18
Then add the unit, we have(18 g/mol.)