The correct option is D.
The major component of rust is Fe2O3. To know the number of atom in one molecule of rust, one have to look at the chemical formula of rust and determine the different atoms that are present and their numbers. Looking at the chemical formula above, one will notice that, two atoms of iron is present and three atoms of oxygen. The number of atoms present are written in front of the chemical symbol of each element. two atoms of iron added to three atoms of oxygen will give 5 atoms. Thus, five atoms are present in one molecule of rust.
The products of self-ionization of water are H3O+ or H+ and OH-
The auto-ionization constant of water is equal to the product of the concentration of H3O+ andOH- . The value of w depends only on temperature. It can be change according to the temperature.
b. atomic number = 8; mass number = 17
c. atomic number = 7; mass number = 17
d. atomic number = 7; mass number = 15
c. Atomic number = 7; mass number = 17
The atomic number of the first isotope is 7.
Isotopes of the same element have the same atomic number, so the atomic number of the second isotope must also be 7.
Mass number = no. of protons + no. of neutrons, or
A = p + n
∴ A = 7 + 10 = 17
Options “a.” and “b.” have the wrong atomic numbers, and option “d.” has the wrong mass number.
Answer:
C
Explanation:
To find the volume ratios we say m1v1=m2v2
where m1 is the initial molarity, m2 the final molarity, v1 the initial volume, v2 the final volume.in this question m1=2.00M, m2=0.40M v2=150ml
Therefore the expression becomes: 2.00M×v1=0.40M×150mL
v1=(0.40M×150mL)/2.00M
=30mL
Endothermic reactions are reactions that proceed by the absorption of heat (energy) while exothermic reactions involve a release of energy.
a) Formation of frost on a car window in winter is an exothermic process as heat is liberated when liquid water freezes to form crystals
b) Formation of water condensate on a glass of ice water is an endothermic reaction since heat is absorbed by the cold water from the glass container thereby cooling it.
c) A decrease in the temperature as ammonium nitrate is added to water is an endothermic reaction
a) and b) are exothermic processes because they release heat to the surroundings. c) is an endothermic process because it absorbs heat from the surroundings.
Let's analyze each option:
a) Frost forms on a car window in winter: Exothermic
Frost forming is an exothermic process because it releases heat as water vapor in the air condenses and freezes on the cold car window, giving off energy in the form of heat to the surroundings.
b) Water condenses on a glass of ice water on a humid summer afternoon: Exothermic
Similar to the first scenario, water condensation is exothermic. As water vapor from the humid air comes into contact with the cold glass of ice water, it condenses into liquid water, releasing heat to the surroundings.
c) Adding ammonium nitrate to water causes the temperature of the solution to decrease: Endothermic
This process is endothermic because dissolving ammonium nitrate in water absorbs heat from the surroundings, causing the temperature of the solution to decrease.
Learn more about exothermic and endothermic processes:
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