a) The E might belong to group 13.
As the formula of a chemical compound is derived by the cross multiplication of the valency of the atoms. As formula of the given oxide is and valency of O atom is -2, therefore valency of element E must be +3 in order to obtain E2O3.
Also, in EF3, the valency of E will be +3 because there are three atoms of fluorine who has an individual valency of -1. Thus, e will have the valency of +3.
The Group 13 is the boron group which has the following elements:
- Boron
- Aluminium
- Gallium
- Indium
- Thallium
All these elements have the valency of +3.
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Explanation
Radius of neon atom : 69 pm = 
Volume occupied by the one atom:
given that 
atoms are present in 1L
1 L = 0.001 
The volume occupied by the neon atoms
Fraction of volume occupied by the neon atom:
The fraction of of volume occupied by the neon atom is very less than the 1 L which indicates the presence of large amount of empty space between the atoms of the gas.
Answer:
V₂ = 1866.32 mL
Explanation:
Given data:
Initial temperature = 27.8°C (27 + 273.15 K = 300.15 k)
Initial volume = 1500 mL
Final volume = ?
Final temperature = 100.0°C (100.0 + 273.15 K = 373.15 K)
Solution:
The given problem will be solve through the Charles Law.
According to this law, The volume of given amount of a gas is directly proportional to its temperature at constant number of moles and pressure.
Mathematical expression:
V₁/T₁ = V₂/T₂
V₁ = Initial volume
T₁ = Initial temperature
V₂ = Final volume
T₂ = Final temperature
Now we will put the values in formula.
1500 mL / 300.15 k = V₂ / 373.15 K
V₂ = 1500 mL× 373.15 K/ 300.15 k
V₂ = 560175 mL. K /300.15 k
V₂ = 1866.32 mL
Magnesium ribbon dissolves in zinc nitrate and copper nitrate solutions.
Even though the question is incomplete and refers to your practical work, however, I will try to help you as much as I can.
Metals dissolves in solutions of other metals that are lower than them in the electrochemical series. Hence, copper strip will show no change in magnesium nitrate or zinc nitrate solution. A zinc strip will not show any change in magnesium nitrate or zinc nitrate.
However, a magnesium ribbon will dissolve very quickly in zinc nitrate and copper nitrate solutions.
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Answer: There are 1566 joules of heat needed to raise the temperature of 30.0 g of aluminum from 22°C to 80°C, if the specific heat of aluminum is 0.90 J/g°C.
Explanation:
Given: Mass = 30.0 g
Specific heat = 
Formula used to calculate the heat energy requires is as follows.
where,
q = heat energy
m = mass of substance
C = specific heat capacity of substance
= initial temperature
= final temperature
Substitute the values into above formula as follows.
Thus, we can conclude that there are 1566 joules of heat needed to raise the temperature of 30.0 g of aluminum from 22°C to 80°C, if the specific heat of aluminum is 0.90 J/g°C.
