What is the Einstein theory of relevancy

The mass number is equal to which of the following? Question 5 options: Protons + Neutrons Protons + Atomic Number Neutrons + El

Sedbober [7]

Answer: The mass number is the sum of the numbers of protons and neutrons present in the nucleus of an atom.

I hope that this helps you !

7 0

3 years ago

A mixture of nacl and sucrose (c12h22o11) of combined mass 10.2 g is dissolved in enough water to make up a 250 ml solution. the

Vilka [71]

We use the osmotic pressure to determine the concentration of the solute in the solution. Then, we multiply the volume of the solution to determine the number of moles of solute particles. We need to establish to equations since we have two unknowns, the mass of of each solute. We do as follows:

osmotic pressure = CRT
C = 7.75 / 0.08205 (296.15) = 0.3189 mol / L
moles of particles = C*V = 0.3189*0.250 =0.0797 mol 
0.0797 = moles of sucrose + 2*moles of salt 

x + 2y = 0.0797 
and 
x(MMsucrose) + y(MMNaCl) = 10.2
342x + 58.5y = 10.2

solve for x and y

x = 0.0252 mol sucrose
y = 0.0273 mol NaCl

mass Sucrose = 0.0252(342) = 8.6184 g 
mass NaCl = 0.0273(58.5) = 1.5971 g 
% NaCl = (1.5971 / 10.2)*100 = 15.66%

4 0

3 years ago

A gaseous mixture composed of 20% CH4, 30% C2H4, 35% C2H2, and 15% C2H20. What is the average molecular weight of the mixture? a

Semenov [28]

Answer: The correct answer is Option d.

Explanation:

We are given:

Mass percentage of $CH_4$ = 20 %

So, mole fraction of $CH_4$ = 0.2

Mass percentage of $C_2H_4$ = 30 %

So, mole fraction of $C_2H_4$ = 0.3

Mass percentage of $C_2H_2$ = 35 %

So, mole fraction of $C_2H_2$ = 0.35

Mass percentage of $C_2H_2O$ = 15 %

So, mole fraction of $C_2H_2O$ = 0.15

We know that:

Molar mass of $CH_4$ = 16 g/mol

Molar mass of $C_2H_4$ = 28 g/mol

Molar mass of $C_2H_2$ = 26 g/mol

Molar mass of $C_2H_2O$ = 48 g/mol

To calculate the average molecular mass of the mixture, we use the equation:

$\text{Average molecular weight of mixture}=\frac{_{i=1}^n\sum{\chi_im_i}}{n_i}$

where,

$\chi_i$ = mole fractions of i-th species

$m_i$ = molar masses of i-th species

$n_i$ = number of observations

Putting values in above equation:

$\text{Average molecular weight}=\frac{(\chi_{CH_4}\times M_{CH_4})+(\chi_{C_2H_4}\times M_{C_2H_4})+(\chi_{C_2H_2}\times M_{C_2H_2})+(\chi_{C_2H_2O}\times M_{C_2H_2O})}{4}$

$\text{Average molecular weight of mixture}=\frac{(0.20\times 16)+(0.30\times 28)+(0.35\times 26)+(0.15\times 42)}{4}\\\\\text{Average molecular weight of mixture}=6.75$

Hence, the correct answer is Option d.

3 0

3 years ago

At a certain temperature the vapor pressure of pure chloroform (CHCl3) is measured to be 91. torr. Suppose a solution is prepare

OleMash [197]

Answer:

$P_{CCl_4}=52.43torr$

Explanation:

Hello there!

In this case, sine the solution of this problem require the application of the Raoult's law, assuming heptane is a nonvolatile solute, so we can write:

$P_{CCl_4}=x_{CCl_4}P_{CCl_4}^{vap}$