Answer:
Yes, they are isotopes.
Explanation:
Isotopes are atoms with the same atomic number Z and a different mass number (A). That is, they differ in the number of neutrons (eg carbon 12, has 6 protons, 6 electrons, and 6 neutrons, carbon 13, 7 neutrons, and carbon 14 8 neutrons).
Explanation:
The given reaction is redox reaction but not combustion reaction.
Redox reaction : It is a chemical reaction in which oxidation and reduction occurs simultaneously.Oxidation is gaining of electrons and reduction is loosing of electrons.
oxidation
reduction
Potassium when reacts with water ,gives potassium ion in aqueous medium and combines with hydroxide ion present in water to form potassium hydroxide where as 
ions of water by gaining electrons (from potassium in water) gives hydrogen gas.
Hence , yes it is a redox reaction
Combustion reaction are the chemical reaction in which one reactant react with oxygen molecule to give heat and light.
Here in given reaction no oxygen molecule is appearing on reactant side.
Hence not a combustion reaction.
Scientists will often use a(n) _________________, an object that helps explain ideas about the natural world.
The answer is model.
The state of the substance, most likely, would be a gas. Given the same amount of the substance being able to fill different volumes of containers, means that the substance is compressible. From the three phases of matter, gas is surely the compressible one while liquids are sometimes compressible but only up to certain extent. Also, the substance cannot be a a solid since a solid would have a definite shape and volume. Nor it cannot be a liquid since a liquid cannot fill the whole container and it does not change its volume no matter what is the container.
<span>The periodic table of elements arranges all of the known chemical elements in an informative array. Elements are arranged from left to right and top to bottom inorder of increasing atomic number.
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