28) All elements are made of atoms
29)Protons and Neutrons
-Electrons make up the outside of the Nucleus
Answer:
Gas X
Explanation:
The given reaction can be written in the form of chemical equation as shown below as:

According to law of conservation of mass, the moles of each substance in the reaction must be equal on both reactant and product side.
Also, the question asks for the gas which is diatomic.
cannot be diatomic as the formula contains 3 atoms.
Between gas X and gas Y , <u>X has to be diatomic for the reaction to balance </u>as:

Answer:
A double bond between carbon atoms
Explanation:
The suffix -ene is used for alkenes, which tells you that the molecule has a carbon-carbon double bond.
Answer:
1.36 × 10³ mL of water.
Explanation:
We can utilize the dilution equation. Recall that:

Where <em>M</em> represents molarity and <em>V</em> represents volume.
Let the initial concentration and unknown volume be <em>M</em>₁ and <em>V</em>₁, respectively. Let the final concentration and required volume be <em>M</em>₂ and <em>V</em>₂, respectively. Solve for <em>V</em>₁:

Therefore, we can begin with 0.640 L of the 2.50 M solution and add enough distilled water to dilute the solution to 2.00 L. The required amount of water is thus:

Convert this value to mL:

Therefore, about 1.36 × 10³ mL of water need to be added to the 2.50 M solution.