Which equation best describes a single-replacement reaction between silver and magnesium chloride?

The reaction q+r2=r2q is found to be first order in r2 and

Match each object to its description: a. coma of a comet b. comet tail c. oort cloud haze surrounding a nucleus created by solar wind. hypothetical sphere around the solar system

In saturated organic compounds, all the bonds between carbon atoms are called?