Answer:
When 0.250 moles of a gas is placed in a container at 25 °C, it exerts a pressure of 700 mm Hg.
Explanation:
Answer is Polonium-218 (84 protons).
alpha decay is an emission of ₂⁴He nucleus. If an element undergoes an alpha decay, the mass of the daughter nucleus formed is reduced by 4 compared to mass of parent atom and atomic number is reduced by 2 compared to atomic number of parent atom.
Since the parent atom has 86 protons, atomic number is 86. Hence, the daughter atom should have 86 - 2 = 84 as atomic number. The parent atom has 222 as its mass. Hence, formed daughter atom should have 222 - 4 = 218 as its mass number.
The reaction for this decay is;
₈₆²²²Rn → ₈₄²¹⁸Po + ₂⁴∝
Answer:
Carbon is a chemical element, like hydrogen, oxygen, lead or any of the others in the periodic table. Carbon is a very abundant element. It exists in pure or nearly pure forms – such as diamonds and graphite – but can also combine with other elements to form molecules.
Answer:- d) 42 kJ of heat is released and the reaction is exothermic.
Solution:- Heat of reaction is the summation of heats of products - reactants.
From given information, the energy contained by products is 352 kJ and the energy contained by reactants is 394 kJ. Let's plug in the values in the formula:
= [352 kJ - 394 kJ]
= -42 kJ
Heat of reaction is -42 kJ. The negative sign indicates the heat is released means the reaction is exothermic.
So, the correct option is the last one, 42 kJ of heat is released and the reaction is exothermic.