all cells come from pre existing cells
Answer: option a and d
Explanation:
Option A- Benzene undergoes substitution reaction
Example : benzene reacts with chlorine to form chlorobenzene, in the presence of Iron
(iii) chloride as a catalyst
C6H6 + Cl2 ---> C6H5Cl + HCl
Option D- Benzene also undergoes addition reaction
Example: benzene reacts with hydrogen , in the presence of nickel as a catalyst to form
cyclohexane
C6H6 + 3H2 ---> C6H12
Reasons why Option B isn't the answer
Although benzeme has degree of unsaturation but it's not five degree of unsaturation.
Benzene has 6 carbon atoms and 4 degrees of unsaturation (1 ring and 3 double
bonds).
If you work backwards and double the degrees of unsaturation you have 8 degrees of
unsaturation instead of 5.
Option C - Benzene isn't a saturated hydrocarbon
Answer: The precipitate formed is 
Explanation:
A double displacement reaction is one in which exchange of ions take place. The salts which are soluble in water are designated by symbol (aq) and those which are insoluble in water and remain in solid or precipitated form are represented by (s) after their chemical formulas.
A double displacement reaction in which one of the product is formed as a solid is called as precipitation reaction.
The balanced chemical equation is:

M(Cs)=133 g/mol
M(O)=16 g/mol
M(CsxOy)=298 g/mol
w(Cs)=0.89
w(O)=0.11
CsxOy
x=M(CsxOy)w(Cs)/M(Cs)
x=298*0.89/133=2
y=M(CsxOy)w(O)/M(O)
y=298*0.11/16=2
Cs₂O₂ cesium peroxide
Answer:
0.85 mole
Explanation:
Step 1:
The balanced equation for the reaction of CaCl2 to produce CaCO3. This is illustrated below:
When CaCl2 react with Na2CO3, CaCO3 is produced according to the balanced equation:
CaCl2 + Na2CO3 -> CaCO3 + 2NaCl
Step 2:
Conversion of 85g of CaCO3 to mole. This is illustrated below:
Molar Mass of CaCO3 = 40 + 12 + (16x3) = 40 + 12 + 48 = 100g/mol
Mass of CaCO3 = 85g
Moles of CaCO3 =?
Number of mole = Mass /Molar Mass
Mole of CaCO3 = 85/100
Mole of caco= 0.85 mole
Step 3:
Determination of the number of mole of CaCl2 needed to produce 85g (i.e 0. 85 mole) of CaCO3.
This is illustrated below :
From the balanced equation above,
1 mole of CaCl2 reacted to produced 1 mole of CaCO3.
Therefore, 0.85 mole of CaCl2 will also react to produce 0.85 mole of CaCO3.
From the calculations made above, 0.85 mole of CaCl2 is needed to produce 85g of CaCO3