True or false: Denaturation of an enzyme increases the rate at which it may catalyze a chemical reaction.

Answer : The density of iron is, 7.8 g/mL

Explanation : Given,

Mass of iron = 4.7 g

Volume of water = 27.10 mL

Volume of water and iron = 27.70 mL

First we have to calculate the volume of iron.

Volume of iron = Volume of water and iron - Volume of water

Volume of iron = 27.70 mL - 27.10 mL

Volume of iron = 0.6 mL

Now we have to calculate the density of iron.

Now put all the given values in this expression, we get:

Thus, the density of iron is, 7.8 g/mL

To calculate this, we need the molar mass of water which is obtaine by adding the molar masses of the elements. For H2O, the molar mass is 18.02g/mol. Then, from the amount given which is 1 gram of H2O we divide the molar mass which yields to 0.06 mol of water.

Answer: Option (b) is the correct answer.

Explanation:

An open system is defined as the one where there will occur exchanges of matter as well as heat energy between the system and surrounding.

For example, when a boil water then its heat energy will move into the surrounding and also matter is moving to the surrounding in the form of water vapor or steam.

On the other hand, a system in which there will occur no exchange of matter but exchange of heat will occur from the system to the surrounding is known as a closed system.

For example, coffee placed in a cup covered with lid is a closed system.

Thus, we can conclude that the statement heat and matter are both able to enter or leave the system best expresses the definition of an open system.

The mass percentage of vitamin C is 74.5% and the mass percentage of sucralose is 25.5%.

Osmotic pressure (π) = iCRT

Where;

π = Osmotic pressure = 3.18 atm

i = Van't Hoff factor = 1 (molecular solution)

C = concentration (in mol/L)

R = gas constant = 0.082 LatmK-1mol-1

T = temperature =  287 K

But C = number of moles(n) /Volume (V)

volume = 41.1 mL or 0.0411 L

Substituting into the given equation;

π = n/V × RT

Make n the subject of the formula;

n = πV/RT

n = 3.18 atm ×  0.0411 L/0.082 LatmK-1mol-1 × 287 K

n = 0.0056 moles

Mass of vitamin C = a

Mass of sucralose = b

Mass of sample = 1.149 g

Hence;

a + b = 1.149

b = 1.149 - a

Molar mass of vitamin C = 176 g/mol

Molar mass of sucralose = 398 g/mol

Total number of moles = number of moles of vitamin C + number of moles of sucralose

 0.0056  moles = a/176  + (1.149 - a)/398

70048 ( 0.0056 ) = 398a + 176 (1.149 - a)

392.269 = 398a + 202.224 - 176a

392.269 - 202.224 = 398a  - 176a

190.045 = 222a

a = 190.045/222

a = 0.856 g

But;

b = 1.149 - a

Where a =  0.856 g

b = 1.149 - 0.856

b = 0.293 g

Mass percent vitamin C =  0.856 g/1.149 g × 100/1

= 74.5%

Mass percent sucralose = 0.293/1.149 g × 100/1

= 25.5%

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