Answer:
The period 4 alkaline-earth metal has the name Calcium. An isotope of this element having 20 neutrons has a mass number of 40.
Explanation:
Looking at the periodic table 4th row for the alkaline-earth metal, we can find Calcium which has an atomic number of 20 (or protons number, or z). The mass number is given by the sum of protons and neutrons. If the number of protons in this case is 20 and the number of neutrons is also 20, the mass number A = 40.
Answer:
2.77 mL of boiling water is the minimum amount which will dissolve 500 mg of phthalic acid.
Explanation:
We know from the problem that 18 g of phthalic acid are dissolved in 100 mL of water at 99 °C.
Now we devise the following reasoning:
If 18 g of phthalic acid are dissolved in 100 mL of water at 99 °C
Then 0.5 g of phthalic acid are dissolved in X mL of water at 99 °C
X = (0.5 × 100) / 18 = 2.77 mL of water
Answer:
2.5 mol Cl2 will react with 5 mol Na.
Explanation:
To solve this we assume
that the gas is an ideal gas. Then, we can use the ideal gas equation which is
expressed as PV = nRT. At a constant temperature and number of moles of the gas
the product of PV is equal to some constant. At another set of condition of
temperature, the constant is still the same. Calculations are as follows:
P1V1 =P2V2
P2 = P1 x V1 / V2
P2 = 2.0 x 1.5 / 3
<span>P2 = 1 atm</span>
Answer: Proton will have larger wavelength
Explanation:
(de-Broglie's equation)
h= Planck constant
m= mass of the particle
v= velocity of the particle
As we can see from the de-Broglie's equation , that wavelength is inversely proportional to the product of mass into velocity of the object.
The wavelength of proton will be higher than that fast moving golf ball because mass of proton 
is very small than that of the golf ball (45.93 g). Proton is moving at slow velocity and the golf ball is moving with fast velocity by which value of product of mass into velocity of proton will be lower than the value of product of mass into velocity of the golf ball which will result in larger value of wavelength of the proton.
