The emission spectrum of a chemical element
A= mass number = number of protons and neutrons in the nucleus
Z= number of electrons = number of protons
Given, number of neutrons= 30
Z = A - 30 = 70 - 30 = 40
Z = 40
I hope I was helpful
For the reaction to take place the energy of the reactants must reach to the energy level of the products:
we have 900 J in the reactants and 9000 J for the products so the reactants need 8100 J to reach to the value of energy of products (900 + 8100 = 9000)
So the correct answer is C. <span>The reaction absorbs 8100 J of energy from the surroundings as it proceeds. </span>
The correct answer is B. Solubility describes the amount of solute that can be dissolved in a solvent. This value is not constant is affected by many factors. One factor is the temperature. An increase in temperature, a corresponding change in solubility also can be observed. The increase leads to a decrease in the solubility and the opposite. A decrease is observed since gas molecules are now has enough energy to escape the liquid phase and go to the gas phase.
