Answer:
a. 52.8
Explanation:
To find the number of moles of HCl we use the relation M₁V₁=M₂V₂
where M₁ is the initial molarity, M₂ the new molarity, V₁ the initial volume used, and V₂ the final volume obtained.
M₁=7.91 M
M₂=2.13 M
V₁=?
V₂=196.1 mL
Replacing these values in the relationship.
M₁V₁=M₂V₂
7.91 M× V₁=2.13 M×196.1 mL
V₁=(2.13 M×196.1 mL)/7.91 M
=52.8 mL
As we know,
Density of Benzene = 876 Kg/m³
And,
Density of Water = 997 Kg/m³
So,
Specific Gravity is calculated as,
Specific Gravity = Density of Benzene / Density of Water
Specific Gravity = 876 Kg/m³ / 997 Kg/m³
Specific Gravity = 0.878
Every object having specific gravity less than 1 will float on water and if value is greater than 1 then it will sink.
Benzene being non-polar in nature does not mix with water and due to less density it will float on the surface of water.
Answer:
d. Radon-222
Explanation:
²²⁶₈₈Ra → ²²²₈₆Rn + ⁴₂He
Alpha particle is a helium nucleus with mass number 4 and atomic number 2. According to the law of conversation of mass, the sum of the mass number and atomic number must be equal on both side of the reaction.
Since the mass number of Ra is 226 and that of He is 4. The mass number of the unknown element must be 226 - 4 = 222.
Since the atomic number of Ra is 88 and that of He is 2. The atomic number of the unknown element must be 88 - 2 = 86.
Now looking in the periodic table Radon is the only element with atomic number 86.
