Well, look up the atomic weights of copper and oxygen; add them appropriately; divide the total for the copper by the total for the molecule; then multiply by 100 to get it as a percentage.
Answer:
C.) Argon
Explanation:
This is because ionisation energy increases as we move from left to right in a period. Argon presents in the right most column and Argon is a novel gas and has 8 electrons in outermost orbital. So, it is highly stable. I hope I helped! ^-^
Answer:
Is B, it is B because you don't need arrows on it.
The balloon's volume at 35°C : V₂=31.01 L
<h3>Further explanation</h3>
Given
T₁ = 25°C+273 = 298 K
V₁ = 30 L
T₂ = 35 °C + 273 = 308 K
Required
The new volume (V₂)
Solution
Charles's Law
When the gas pressure is kept constant, the gas volume is proportional to the temperature

Input the value :
V₂=(V₁.T₂)/T₁
V₂=(30 x 308)/298
V₂=31.01 L
You need the Avogadro's number. I can't remember exactly the calculation.