Answer:
C. 8 eV
Explanation:
In atoms, the energy of each level is quantised. That is one of the reasons why an electron can not exist between energy levels. Thus, when the electron absorbs energy of 8 ev, it get excited and jumps to energy level 2 which has the current value of energy of the electron.
Thus for the electron to move back to its initial energy level, it must emit the exact energy absorbed for its excitation. Therefore, the likely energy of the photon that will be emitted is 8 ev. This would make the electron to have energy that would make it to exist on energy level 1.
Mass of strontium = 88 g
Atomic mass of Sr = 87.62 u
Moles = mass /atomic mass
Moles of Sr = 88 / 87.62 = 1.004
Mass of bromine = 160 g
Atomic mass of Br = 79.904 u
Molar mass of Br₂ = 79.904 x 2 = 159.808 g/mol
Moles = mass /molar mass
Moles of Br₂ = 160 / 159.808 = 1.001
The balanced chemical equation of the reaction between strontium and bromine:
Sr(s) + Br₂(l) = SrBr₂
The molar ratio between Br₂ and SrBr₂ is 1:1
So the moles of SrBr₂ produced from 1.001 moles of Br₂ is 1.001.
Moles = mass /molar mass
Mass = moles x molar mass
Molar mass of SrBr₂ = 247.4280 g/mol
Mass = 1.001 mol x 247.4280 g/mol
Mass = 247.428 g
The mass of strontium bromide produced is 247.428 g.
Speed is a scalar quantity( quantity having only magnitude). So it doesn't specifies direction. Hence option C.) 5Km/hr north is incorrect.
