Answer: C.
Explanation:
The rusting of Clara's bike in which iron changes to rust is a chemical change. In a chemical change: the process is not easily reversible.
An ionic compound forms when a metal bonds with a non-metallic element. Metals usually form the cation and non-metal anions. Chromium has an oxidation number of +3 in the compound and charge on hydroxide ion is -1.
Cation here is 
Anion is the hydroxide ion 
So the formula of the compound will be: 
. The compound has one chromium atom and two hydroxide ions.
Therefore, there will be one Chromium atom per each chromium hydroxide compound.
Answer: It was known as the SPACE RACE.
Explanation: The space race was a cold war between the Soviet Union (USSR) and the United States (US), to get satellites and humans into space. The competition began in earnest on August 2, 1955, when the Soviet Union responded to the US announcement. On April 12, 1961, the USSR surprised the world again by launching Yuri Gagarin into a single orbit around the Earth in a craft they called Vostok 1.
Explanation:
What will the question be ?
Answer:
Potassium cation = K⁺²
Explanation:
The metal cation in K₂SO₄ is K⁺². While the anion is SO₄²⁻.
All the metals have tendency to lose the electrons and form cation. In given compound the metal is potassium so it should form the cation. The overall compound is neutral.
The charge on sulfate is -2. While the oxidation state of potassium is +1. So in order to make compound overall neutral there should be two potassium cation so that potassium becomes +2 and cancel the -2 charge on sulfate and make the charge on compound zero.
2K⁺² , SO₄²⁻
K₂SO₄
