Determine the number of moles of 3.6 g of water [H=1, O=16]. An object has a volume of 2.50 m3 and a density of 10.0 kg m-3. What is the mass of the object? The function of a switch in a circuit is to Which of the following machines is a second class lever?

Given atomic masses: H = 1, O = 16.
Molar mass of $\text{H}_2\text{O} = (2 \times 1) + 16 = 2 + 16 = 18\,g/mol$.

$\text{Number of moles} = \frac{\text{mass}}{\text{molar mass}}$.

• C. $\mathbf{0.20\,mol}$

16. An object has a volume of $2.50\,m^3$ and a density of $10.0\,kg\,m^{-3}$. What is the mass of the object?

Given volume $V = 2.50\,m^3$.
Given density $\rho = 10.0\,kg\,m^{-3}$.
The formula for density is $\rho = \frac{m}{V}$, where $m$ is mass.

• B. $\mathbf{25.0\,kg}$

17. The function of a switch in a circuit is to

• A switch is a device used to make or break an electrical circuit. By opening or closing the circuit, it controls the flow of current, effectively turning the current on or off.
• A. turn off the current

18. Which of the following machines is a second class lever?

• In a second-class lever, the load is located between the fulcrum and the effort.
• A wheelbarrow is a classic example: the wheel acts as the fulcrum, the load is in the middle, and the effort is applied at the handles.
• D. Wheelbarrow