Answer:
Option B is correct.
4
Explanation:
We know that an atom consist of electron, protons and neutrons. Protons and neutrons are present with in nucleus while the electrons are present out side the nucleus.
All these three subatomic particles construct an atom. A neutral atom have equal number of proton and electron. In other words we can say that negative and positive charges are equal in magnitude and cancel the each other. For example, if neutral atom has 6 protons than it must have 6 electrons. The sum of neutrons and protons is the mass number of an atom while the number of protons are number of electrons is the atomic number of an atom.
In given problem we are given with 2 neutrons of helium. We know that the atomic number of He is 2. Thus Mass number of He is,
Number of neutrons + number of proton
2 + 2 = 4
Thus, option B is correct.
Answer: The pH will be 3.87
Explanation:
pH or pOH is the measure of acidity or alkalinity of a solution.
pH is calculated by taking negative logarithm of hydrogen ion concentration.
![pH=-\log [H^+]](https://tex.z-dn.net/?f=pH%3D-%5Clog%20%5BH%5E%2B%5D)
According to stoichiometry,
1 mole of 
gives 1 mole of 
Thus 
moles of gives =
moles of
Putting in the values:
![pH=-\log[0.000134]](https://tex.z-dn.net/?f=pH%3D-%5Clog%5B0.000134%5D)
Thus the pH will be 3.87
Answer:
0.007 g of deprenyl dose is required fro the patient with body mass of 70 kilograms.
Explanation:
The dose for treating Parkinson’s disease = 100 μg/kg body weight
Mass of patient's body = 70 kg
Amount of dose of deprenyl required = 100 μg/kg × 70 kg = 7,000 μg
1 μg = 0.00001 g
7,000 μg = 7,000 × 0.000001 g = 0.007 g
0.007 g of deprenyl dose is required fro the patient with body mass of 70 kilograms.
Answer:
0.07 g/s.
Explanation:
From the question given above, the following data were obtained:
Mass lost = 9.85 g
Time taken = 2 min 30 s
Mean rate =?
Next, we shall convert 2 min 30 s to seconds (s). This can be obtained as follow:
1 min = 60 s
Thus,
2 min = 2 × 60 = 120 s
Therefore,
2 min 30 s = 120 s + 30 s = 150 s
Finally, we shall determine the mean rate of the reaction. This can be obtained as illustrated below:
Mass lost = 9.85 g
Time taken = 150 s
Mean rate =?
Mean rate = mass lost / time taken
Mean rate = 9.85 / 150
Mean rate = 0.07 g/s
Therefore, the mean rate of the reaction is 0.07 g/s
