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According to the law of conservation of Mass:
In a chemical reaction mass can neither be created nor be destroyed
So, we can say that: Mass of A + Mass of B = Mass of C
In the given reaction,
One of the reactants weigh 5 grams and another one weighs x grams
The mass of the product of this reaction is 9 grams
<u>Mass of reactant B:</u>
Mass of A + Mass of B = Mass of C
5 + x = 9
x = 4 grams
Answer:
There are often not more than one or two independent variables tested in an experiment.
Ionic bond is a chemical bond formed by the complete transfer of electrons between two atoms. The atom that loses electrons gains a positive charge (cation) and that which accepts electrons gains a negative charge (anion). Now, electronegativity is a parameter that measures the tendency of an atom to accept electrons. In the context of ionic bonding, two elements which show a significant difference in their electronegativity values form ionic bonds.
In the given examples, the difference in electronegativity is greatest between K and Br i.e. 0.8 and 2.8 respectively with a difference of 2.0. This also makes sense since K and Br are on the extreme ends of the periodic table. Hence, potassium with a valence electron configuration of 4s1 will lose its s electron to Br (4s24p6) and form an ionic molecule K⁺Br⁻
Ans E) potassium and bromine
Answer:B) a reactant that undergoes reduction
Explanation:
Oxidation reaction is defined as the reaction in which a substance looses electrons. The oxidation state of the substance increases during oxidation.
Reduction reaction is defined as the reaction in which a substance gains electrons. The oxidation state of the substance gets reduced during reduction.

Overall reaction: 
The substance M which itself gets oxidized, reduces other and is called as reducing agent. The substance N which itself gets reduced, oxidizes other and is called as oxidizing agent.