Answer:
A is denser than B as it's volume for the same mass is smaller.
Explanation:
Hello.
In this case, we first need to take into account that the density of each metal A and B is computed by dividing the mass over the volume of each metal which is actually computed by substracting the volume of water from the volume of the water and the solid:

Next, we compute the densities as shown below:

In such a way, A is denser is B as it's volume for the same mass is smaller.
Best regards.
Answer:
191.6 g of CaCl₂.
Explanation:
What is given?
Mass of HCl = 125.9 g.
Molar mass of CaCl₂ = 110.8 g/mol.
Molar mass of HCl = 36.4 g/mol.
Step-by-step solution:
First, we have to state the chemical equation. Ca(OH)₂ react with HCl to produce CaCl₂:

Now, let's convert 125.9 g of HCl to moles using the given molar mass (remember that the molar mass of a compound can be found using the periodic table). The conversion will look like this:

Let's find how many moles of CaCl₂ are being produced by 3.459 moles of HCl. You can see in the chemical equation that 2 moles of HCl reacted with excess Ca(OH)₂ produces 1 mol of CaCl₂, so we state a rule of three and the calculation is:

The final step is to find the mass of CaCl₂ using the molar mass of CaCl₂. This conversion will look like this:

The answer would be that we're producing a mass of 191.6 g of CaCl₂.
Answer:
2.42L
Explanation:
Given parameters:
V₁ = 1.8L
T₁ = 293K
P₁ = 101.3kPa
P₂ = 67.6kPa
T₂ = 263K
Unknown:
V₂ = ?
Solution:
To solve this problem, we are going to use the combined gas law to find the final volume of the gas. The combined gas law expression combines the equation of Boyle's law, Charles's law and Avogadro's law;

All the units are in the appropriate form. We just substitute and solve for the unknown;
101.3 x 1.8 / 293 = 67.6 x V₂ / 263
V₂ = 2.42L
Answer:

Explanation:
Hello.
In this case, given the formula:

Whereas E is the energy, h the Planck's constant and u the frequency of the photon. Thus, solving for it, we obtain:

Or also:

Best regards.
Atoms are composed of electrons in a cloud around a positive nucleus.