Answer:
<u>Qustion 7: </u>
Answer is → "c. Calcium ions and sulfate ions join together to form an insoluble compound"
<u>Question 8: </u>
Answer is → b. ²³⁹Pa
<u>Question 9: </u>
Answer is → "c. 1/3 the pressure in container B"
Explanation:
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<u>Qustion 7: </u>
from the graph:
a. precipitation reactions only occur when solution temperature are decreased.
this option is wrong due to precipitation reaction can occur at room temperature or even at elevated temperature.
b. Sodium ions and chloride ions repel each other when they are in a solution.
Also, this is a wrong statement because sodium ions is positively charged and attract the negatively charged chloride ions.
d. the creation of precipitate adds mass that was previously non-existent.
From graph it is clear that the mass doesn't changed before and after the reaction remain constant (=300.23 g).
<u>So, the right answer is</u>
→ "c. Calcium ions and sulfate ions join together to form an insoluble compound"
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<u>Question 8: </u>
According to the equation :
- ²³⁹U → ________+ ₋₁⁰e
- uranium(239) loses a beta particle and so the mass numer will not change ( remains 239).
<u>So, the right answer is</u>
→ b. ²³⁹Pa
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<u>Question 9: </u>
We can use the general law of ideal gas: PV = nRT.
where, P is the pressure of the gas in atm.
V is the volume of the gas in L.
n is the no. of moles of the gas in mol.
R is the general gas constant,
T is the temperature of the gas in K.
If n and T are constant, and have two different values of P and V:
Pₐ * Vₐ= P(b) *V(b)
from the graph:
Vₐ= 9.0 L.
V(b)= 3.0 L.
∴ Pₐ = [P(b) * V(b)] / Vₐ = [P(b) * 3.0 L] / 9.0 L = 1/3 P(b).
<u>So, the right choice is:</u>
Answer is → "c. 1/3 the pressure in container B"
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