Answer : The correct option is A.
Explanation :
Enzyme-catalyzed reaction :
Enzyme act as a biological catalyst and the role of catalyst is to increase the rate of chemical reaction by lowering the activation energy.
Most of the chemical reactions are slow in the absence of enzyme but in the presence of enzyme, the reaction become faster. That means the Enzyme accelerate the rate of reaction.
Therefore, the correct answer is the reaction is faster than the same reaction in the absence of the enzyme.
Answer:
37.5 mL of a 4.0 M Mg(OH)₂ are needed to make 750 mL of 0.2 M Mg(OH)₂
Explanation:
Dilution is the reduction in concentration of a chemical in a solution. Dilution consists of lowering the amount of solute per unit volume of solution.
In other words, dilution is the procedure followed to prepare a less concentrated solution from a more concentrated one, and consists of adding solvent to an existing solution. The quantity or mass of the solute is not changed but only that of the solvent.
In dilutions the expression is used:
Ci*Vi = Cf*Vf
where:
- Ci: initial concentration
- Vi: initial volume
- Cf: final concentration
- Vf: final volume
In this case:
- Ci: 4 M
- Vi: ?
- Cf: 0.2 M
- Vf: 750 mL
Replacing:
4 M* Vi= 0.2 M* 750 mL
Solving:
Vi= 37.5 mL
<u><em>37.5 mL of a 4.0 M Mg(OH)₂ are needed to make 750 mL of 0.2 M Mg(OH)₂</em></u>
In this solution we are having two components i.e. NaCl and H₂O. So the %age mass of NaCl is calculated by following formula,
%age mass of NaCl = (Mass of NaCl / Mass of NaCl + Mass of H₂O) × 100 ------ (1)
Calculating Mass of NaCl at 50°C;
Solubility of NaCl was searched online and was found 36.69 g / 100 mL of water at 50 °C.
Calculating Mass of 100 mL H₂O at 50°C;
Density of H₂O at 50 °C is 0.988 g/ml, so for 100 mL
As,
Density = Mass / Volume
Mass = Density × Volume
Mass = 0.988 g/mL × 100 mL
Mass = 98.8 g
Putting Masses of NaCl and H₂O in eq. 1,
%age mass of NaCl = (36.69 g / 36.69 g + 98.8 g) × 100
%age mass of NaCl = (36.69 g / 135.49 g) × 100
%age mass of NaCl = 27.07 %
