1:2:6? Ba(NO3)2 +Na2SO4 -----> BaSO4 + 2NaNO3
Ba(NO3)2
BaSO4
NaNO 3
Na2SO4
Answer:
0.67 mole
Explanation:
From detailed studies of gases, we have discovered that at stp 1 mole of a gas occupies 22.4L.
With the above discovery, it means that 1 mole of hydrogen gas occupy 22.4L.
Therefore, Xmol of Hydrogen gas will occupy 15L i.e
Xmol of Hydrogen gas = 15/22.4 = 0.67 mole.
Therefore, there are 0.67 mole of Hydrogen gas in 15L of the gas
It will take 28 days to let the radioactivity fall below 25%.
<h3>What is Half Life ?</h3>
Half life can be described as the time required by the radioactive compound to reduce to half of the original value of concentration.
It is given that
Radioactive phosphorus-32 decays with a half-life of 14.0 days
25% of the initial measure at what time =?
For 50% decay the time needed is 14 days
for decay of the next 50% of the amount left the time taken will be another 14 days
2nd half life = 25% decay of the substance = 28 days
Therefore it will take 28 days to let the radioactivity fall below 25%.
To know more about Half Life
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Answer:
The mass of gold is found to be 310.34 g.
Explanation:
We have:
Specific heat of gold = C = 0.130 J/g.°C
Heat = H = 468 J
Change in Temperature = ΔT = 33.2 °C - 21.6 °C = 11.6 °C
Now, to find mass of gold we first calculate the amount of heat required to heat the unit mass of gold to specified temperature:
Mass Specific Heat = C * ΔT
Mass Specific Heat = (0.130 J/g.°C)(11.6 °C)
Mass Specific Heat = 1.508 J/g
Now, for the mass of gold (m):
mass of gold = Heat/Mass Specific Heat
mass of gold = 468 J/1.508 J/g
<u>mass of gold = 310.34 g</u>
Answer:
Option C is the correct. Valence electrons have a higher energy level than those in other filled shells
Explanation:
Electrons must lose energy to move from the first to the second shell. FALSE
The electrons always win energy to move from the first to the second shell.
All the electrons in an atom have similar energy levels FALSE.
They are not neccesary similar. In hydrogen these are the level energy -13.6 eV
, -3.4 eV
, -1.51 eV
, -85 eV and -54 eV
Electrons do not have potential energy, just kinetic energy. FALSE
They have both.
Valencia electrons are the last electrons in the last layer. They have as much energy as possible and are responsible for forming bonds with other elements.