Answer:
first number is the correct answer
Answer:When you look at the periodic table, each row is called a period (Get it? Like PERIODic table.). All of the elements in a period have the same number of atomic orbitals. For example, every element in the top row (the first period) has one orbital for its electrons.
Explanation:
Open system is a system in which mass or energy can be lost to or gained from the environment. In this case, water and power come from external sources best explains why a washing machine would be considered an open system.
Answer:

Explanation:
From the question we are told that:
Mass of mixture 
Mass of Barium 
Equation of Reaction is given as

Generally the equation for Moles of Barium is mathematically given by
Since

Therefore

Generally the equation for Mass of Barium is mathematically given by

Therefore

