Blue, white, yellow, orange, red
Answer:
Demonstration 1 showed a chemical change because a new gaseous substance was formed, and demonstration 2 showed a physical change because liquid water became water vapor.
Explanation:
Chemical changes alter the chemical makeup of a subject, and a physical change only alters the appearance of a subject, not the chemical makeup.
Answer:
In 23.49 minutes the concentration of A to be 66.8% of the initial concentration.
Explanation:
The equation used to calculate the constant for first order kinetics:
.....(1)
Rate law expression for first order kinetics is given by the equation:
......(2)
where,
k = rate constant
=Half life of the reaction = 
t = time taken for decay process = ?
= initial amount of the reactant = 0.163 M
[A] = amount left after time t = 66.8% of ![[A_o]](https://tex.z-dn.net/?f=%5BA_o%5D)
[A]=


t = 1,409.19 s
1 minute = 60 sec

In 23.49 minutes the concentration of A to be 66.8% of the initial concentration.
Answer:
Sn + 4HNO3 → SnO2 + 4NO2 + 2H2O
Explanation:
An element is a substance that can not be broken into simpler parts by chemical means. Elements are made up of atoms. A molecule is the smallest particle of an element or a compound that has the same properties as the element or the compound. A molecule is made up of two or more atoms . A substance may be an element and a molecule. In this case the answer is, H2 (hydrogen gas) which is a molecule with two atoms of hydrogen and an element.