The Missouri Compromise and the Compromise of 1850 were both meant to stop the spread of slavery in the US.

create a compromise in which new states could be admitted to the union.

allow slavery to move into the Louisiana Territory.

create a compromise in which new states could be admitted to the union.

Explanation:

It was meant to keep the balance between how many slave & free states there were.

The First Question: create a compromise in which new states could be admitted to the union.

The Second Question: California was seeking admittance to the union as a free state.

Explanation:

radioactive dating, also known as  radioisotope dating  is a process that in  estimating the approximate  age  of  rocks. these data can be analyzed from  the studies dealing with the  decay of the radioactive elements that are present in these rocks. in nature, there are a few types of materials or atoms which are quite unstable and they spontaneously decay or breakdown to form other kinds of atoms.

the answer to your question is a. the salt plains

in 1811, he led an expedition, known as the george c. sibley expedition, to improve relations with the pawnee and kansa tribes, and also to locate the rumored jefferson's salt mountain