Which two samples of gas at stp contain the same total number of molecules?

D) 2L of H2 & 2L of Cl2

Explanation:

As according to universal gas law,

PV=nRT

V=nRT/P

For STP condition, T=273.15K, P=1atm n= 1mole

R=0.0819 L atm / mol K

V= 1*0.082*273.15/1 = 22.4 L

So 1 mole of gas at STP has 22.4L of volume

we know, No. of molecules= no of moles* Avogadro's Number

A) 1L of CO & 0.5L of N2

1L of CO:  

Number of moles in 22.4L of CO = 1

Number of moles in 1L of CO = 1/22.4=0.045 moles

Number of molecules in 1L of CO= 0.045*Avogadro's Number

0.5L of N2

Number of moles in 22.4L of N2= 1

Number of moles in 0.5L of N2= 1/22.4=0.022 moles

Number of molecules in 0.5L of N2= 0.022*Avogadro's Number

So both are not equal, A is not our answer

B) 2L of CO & 0.5L of NH3

1L of CO:  

Number of moles in 22.4L of CO = 1

Number of moles in 2L of CO = 2/22.4=0.089 moles

Number of molecules in 2L of CO= 0.089*Avogadro's Number

0.5L of NH3

Number of moles in 22.4L of NH3= 1

Number of moles in 0.5L of NH3= 1/22.4=0.022 moles

Number of molecules in 0.5L of N2= 0.022*Avogadro's Number

So both are not equal, B is not our answer

C) 1L of H2 & 2L of Cl2

1L of H2:  

Number of moles in 22.4L of H2 = 1

Number of moles in 1L of H2 = 1/22.4=0.045 moles

Number of molecules in 1L of H2= 0.045*Avogadro's Number

2L of Cl2

Number of moles in 22.4L of Cl2= 1

Number of moles in 2L of Cl2= 1/22.4=0.089 moles

Number of molecules in 2L of Cl2= 0.089*Avogadro's Number

So both are not equal, C is not our answer

D) 2L of H2 & 2L of Cl2

2L of H2:  

Number of moles in 22.4L of H2 = 1

Number of moles in 1L of H2 = 2/22.4=0.045 moles

Number of molecules in 2L of H2= 0.089*Avogadro's Number

2L of Cl2

Number of moles in 22.4L of Cl2= 1

Number of moles in 2L of Cl2= 1/22.4=0.089 moles

Number of molecules in 2L of Cl2= 0.089*Avogadro's Number

So both are not equal, D is our answer

explanation:

let the different atoms be x and y. each with four protons and same mass will be represented as follows.

mass number is number of protons + number of neutrons.

            and  

since, it is given that one has a negative charge while the other is neutral. therefore, there will be increase in number of protons and the atom will be represented as follows.

according to periodic table, mass number of beryllium is 9 and it has atomic number 4 so, the atoms will be and .  

the protons and neutrons will be located inside the nucleus whereas the electrons will be revolving around the nucleus.