Answer : The volume for 6.0m HCl solution required = 62.5 ml
Solution : Given,
Initial concentration of HCl solution = 6.0m
Final concentration of HCl solution = 1.5m
Final volume of HCl solution = 250 ml
Initial volume of HCl solution = ?
Formula used for dilution is,

where,
= initial concentration
= final concentration
= initial volume
= final volume
Now put all the given values in above formula, we get the initial volume of HCl solution.

= 62.5 ml
Therefore, the volume for 6.0m HCl solution required = 62.5 ml
Answer:
165 of CO₂.
Explanation:
In the reaction:
Na2CO3 + 2HCl → 2NaCl + CO2 + H2O
2 moles of HCl reacts producing 1 mole o CO₂
If 7.5 moles of HCl reacts, moles of CO₂ produced are:
7.5 moles of HCl ₓ ( 1 mol CO₂ / 2 mol HCl) = 3.75 mol CO₂. As molar mass of CO₂ is 44g/mol, mass of CO₂ is:
3.75 mol CO₂ ₓ (44g / 1mol) = <em>165 of CO₂ </em>
C, it prevents the Earth from ultraviolet radiation and other harmful substances from space