Electronegativity decreases as you go down a colum in the periodic table.
Hello!
The observation that would provide the best evidence that a chemical reaction occurred is that The baking soda and hydrochloric acid combined, and bubbles formed.
When baking soda (NaHCO₃) and Hydrochloric Acid (HCl) combine, the following reaction happens:
NaHCO₃ + HCl → NaCl + H₂O + CO₂(g)↑
The gaseous Carbon Dioxide (CO₂) generated in this reaction is the responsible for the bubbles. The releasing of this gas is an evidence that a chemical reaction occurred between NaHCO₃ and HCl.
Have a nice day!
Answer:
Option a: positron emission.
Explanation:
In the transformation we have:
⁶⁷Ga → ⁶⁷Zn
The reaction is:

For Ga to become Zn, the atom nucleus has to lose a proton, so in the given options, the reaction that involves the transformation of a proton is the option a, positron emission.
In a positron emission, a proton becomes into a neutron and a positron:

Therefore, the correct answer is option a: positron emission.
I hope it helps you!
Answer:

Explanation:
Hello there!
In this case, according to the given question about stoichiometry, it is possible for us to calculate the required moles of water that will be produced by 12 grams of hydrogen, by using the molar mass of this reactant (2.02 g/mol as it is diatomic) and the 2:2 mole ratio in the chemical equation by solving the following setup:

Regards!
Answer:
You should start with 63.54 grams of copper.
Explanation:
The chemical reactions are processes in which the nature of the substances changes, that is, from some initial substances called reactants, totally different ones called products are obtained.
In the chemical reaction, the formulas of reagents and products appear preceded by numbers (the stoichiometric coefficients) that indicate the proportions according to which the transformation occurs. So you can say that stoichiometry establishes relationships between the molecules or elements that make up the reactants of a chemical equation with the products of said reaction. The relationships that are established are MOLAR relationships between the compounds or elements that make up the chemical equation: always in MOLES.
The stoichiometric coefficients of a chemical equation are due to the fact that the atoms present before the reaction must be the same after the reaction, although they will have been rearranged to produce new substances.
If you want 2 moles of silver (Ag), for stoichiometry of the reaction you need a moles of copper Cu. Being the molar mass of copper Cu 63.54 g / mole, then:
1 mole*63.54 g/mole= 63.54 g
<u><em>
You should start with 63.54 grams of copper.</em></u>
<u><em></em></u>