Half life is 100 years.
after 1st life the number of isotopes remaining =100/2=50
after 2nd half life the number of isotopes remaining=50/2=25
Answer:
1 mol of copper
Explanation:
The mass of the oxide formed is the total mass less the crucible mass, so it is:
100.52 - 88.00 = 12.52 g
It means that 10.00 g is from copper, and 2.52 g is from oxygen. The molar mass of copper is 63.50 g/mol, and the molar mass of oxygen is 16 g/mol. The number of moles (n) is the mass divided by the molar mass:
n Cu = 10.00/63.50 = 0.158 moles
n O = 2.52/16 = 0.158 moles
So, there is the same number of moles of each element, and the product must be: CuO, which has 1 mol of copper.
Answer:
C. Its oxidation number increases.
Explanation:
- <em><u>Oxidation is defined as the loss of electrons by an atom while reduction is the gain of electrons by an atom</u></em>.
- Atoms of elements have an oxidation number of Zero in their elemental state.
- When an atom looses electrons it undergoes oxidation and its oxidation number increases.
- For example, <em><u>an atom of sodium (Na) at its elemental state has an oxidation number of 0. When the sodium atom looses an electrons it becomes a cation, Na+, with an oxidation number of +1 , the loss of electron shows an increase in oxidation number from 0 to +1.</u></em>
Answer:
Insulators
Explanation:
Insulators consists of air, water etc.
Answer:
- 0.0413°C ≅ - 0.041°C (nearest thousands).
Explanation:
- Adding solute to water causes the depression of the freezing point.
<em>ΔTf = Kf.m,</em>
Where,
ΔTf is the change in the freezing point.
Kf is the freezing point depression constant (Kf = 1.86 °C/m).
m is the molality of the solution.
<em>Molality is the no. of moles of solute per kg of the solution.</em>
- <em>no. of moles of solute (glucose) = mass/molar mass</em> = (8.44 g)/(180.156 g/mol) = <em>0.04685 mol.</em>
<em>∴ molality (m) = no. of moles of solute/kg of solvent</em> = (0.04685 mol)/(2.11 kg) = <em>0.0222 m.</em>
∴ ΔTf = Kf.m = (1.86 °C/m)(0.0222 m) = 0.0413°C.
<em>∴ The freezing point of the solution = the freezing point of water - ΔTf </em>= 0.0°C - 0.0413°C = <em>- 0.0413°C ≅ - 0.041°C (nearest thousands).</em>
