Answer:
a pencil being sharpened
freezing water
boiling water
Explanation:
a physical change doesn't change the chemical structure of an object. That is why the other 2 are wrong
Answer: 68
Explanation:
Isotopes of an element have same number of protons but different number of neutrons. Which means isotopes of an element have same atomic number but different mass number.
Atomic number is equal to the number of protons or the number of electrons for a neutral atom and is specific to a particular element.
Mass number is the sum of number of protons and the number of neutrons.
Given : atomic number of element Q = 68 = number of protons
Mass number of isotope Q-136 = 136
But as isotopes have same atomic number, the number of protons will be same and hence there are 68 protons are in a neutral atom of this isotope.
Answer:
acetic acid, sodium hydroxide
Explanation:
A strong acid is an acid that ionizes in water to give all its hydrogen ion. Weak acid only ionize to a certain degree. Acetic acid (CH3COOH) only ionize to give one hydrogen ion despite having other hydrogen atom. This account for its weak nature as an acid as shown below:
CH3COOH <=> H^+ + CH3COO^-
A strong base is a base that ionizes in water to give all it hydroxide ion. Sodium hydroxide(NaOH) ionizes to give all its hydroxide ions. This make it a strong base as shown below;
NaOH <=> Na^+ + OH^-
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