<u>Answer:</u> The main group metal produce a basic solution in water and the reaction is 
<u>Explanation:</u>
Main group elements are the elements that are present in s-block and p-block.
The metals that are the main group elements are located in Group IA, Group II A and Group III A.
Oxides are formed when a metal or a non-metal reacts with oxygen molecule. There are two types of oxides which are formed: Acidic oxides and basic oxides.
- Acidic oxides are formed by the non-metals.
- Basic oxides are formed by the metals.
When a metal oxide is reacted with water, it leads to the formation of a base.
The general formula of the oxide formed by Group II-A metals is 'MO'
The chemical equation for the reaction of metal oxide of Group II-A and water follows:

Hence, the main group metal produce a basic solution in water and the reaction is 
Density (p) is defined as the mass (m) per unit volume (v) or:
p = m/v
Using this relationship, the volume is:
v = m/p
Using the given values of mass of 80 grams and density of 8 g/cm3, the sample volume is:
v = 80 grams/8 grams/cm3
v = 10 cm3
The final answer is 10 cm3.
Answer:
1) Exothermic.
2) 
3) 
Explanation:
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1) In this case, for these calorimetry problems, we can realize that since the temperature increases the reaction is exothermic because it is releasing heat to solution, that is why the temperature goes from 22.0 °C to 28.6 °C.
2) Now, for the total heat released by the reaction, we first need to assume that all of it is absorbed by the solution since it is possible to assume that the calorimeter is perfectly isolated. In such a way, it is also valid to assume that the specific heat of the solution is 4.184 J/(g°C) as it is mostly water, therefore, the heat released by the reaction is:

3) Finally, since the enthalpy of reaction is calculated by dividing the heat released by the reaction over the moles of the solute, in this case LiCl, we proceed as follows:

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Given :
0.00072 M solution of
at
.
To Find :
The concentration of
and pOH .
Solution :
1 mole of
gives 2 moles of
ions .
So , 0.00072 M mole of
gives :
![[OH^-]=2 \times 0.00072\ M](https://tex.z-dn.net/?f=%5BOH%5E-%5D%3D2%20%5Ctimes%200.00072%5C%20M)
![[OH^-]=0.00144\ M](https://tex.z-dn.net/?f=%5BOH%5E-%5D%3D0.00144%5C%20M)
![[OH^-]=1.44\times 10^{-3}\ M](https://tex.z-dn.net/?f=%5BOH%5E-%5D%3D1.44%5Ctimes%2010%5E%7B-3%7D%5C%20M)
Now , pOH is given by :
![pOH=-log[OH^-]\\\\pOH=-log[1.44\times 10^{-3}]\\\\pOH=2.84](https://tex.z-dn.net/?f=pOH%3D-log%5BOH%5E-%5D%5C%5C%5C%5CpOH%3D-log%5B1.44%5Ctimes%2010%5E%7B-3%7D%5D%5C%5C%5C%5CpOH%3D2.84)
Hence , this is the required solution .
Answer:
CH4
- 4 electron
- 0 electron
- the geometry of Ch4 is tetrahedral
AlF3
- 3 electron
- 0 electron
- the geometry is trigonal planar
CCl4
- 4 electron
- 0 electron
- the geomotry is tetrahedral
SeH2
- 2 electron
- 2 electron
- the geometry is V shape