Answer:
A is the answer; 'more-efficient extraction techniques
Explanation:
I just took the test and got it right :D
Answer:
THE VOLUME OF 0.200M CALCIUM HYDROXIDE NEEDED TO NEUTRALIZE 35 mL of 0.050 M NITRIC ACID IS 43.75 mL.
Explanation:
Using
Ca VA / Cb Vb = Na / Nb
Ca = 0.0500 M
Va = 35 mL
Cb = 0.0200 M
Vb = unknown
Na = 2
Nb = 1
Equation for the reaction:
Ca(OH)2 + 2HNO3 --------> Ca(NO3)2 + 2H2O
So therefore, we make Vb the subject of the equation and solve for it
Vb = Ca Va Nb / Cb Na
Vb = 0.0500 * 35 * 1 / 0.0200 * 2
Vb = 1.75 / 0.04
Vb = 43.75 mL
The volume of 0.02M calcium hydroxide required to neutralize 35 mL of 0.05 M nitric acid is 43.75 mL
D. 6 protons and 7 neutrons
As proton remains constant
For this, we first calculate molecular weight of MgSiO₃:
Atomic masses:
Mg = 24
Si = 28
O = 16
Mr = 24 + 28 + 16 x 3
Mr = 100
moles = mass / Mr
moles = 237 / 100
moles = 2.37
1.0 mole ---------- 6.02x10²³ molecules
4.5 moles -------- ?
4.5 * 6,02x10²³ / 1.0
= 2.709x10²⁴ molecules units