______________ is a durable metal and is widely used for casting, which is a process by which melted metal is poured into a mold.a. Bronze
c. Copper
b. Silver
d. Gold Please select the best answer from the choices provided A B C D

Answer:

C.

Explanation:

Molecules with the stronger intermolecular forces are pulled tightly together  to form solid at higher temperatures and that's why the freezing point is higher.

Also, molecules with the stronger intermolecular force have greater interaction between the molecules and thus on heating do not boil easily and have high boiling point also.

Thus, melting point and boiling point increases with increase in number of carbon atoms and also increase in intermolecular forces (like hydrogen bonding, if present).

Thus, the compound which is gas at room temperature is because it has least number of carbon atoms and absence of hydrogen bonding.

Final answer:

Among the choices, only CH3CH2CH3 (propane) is a gas at room temperature. The other compounds, CH3CH2OH (ethanol), CH3CH2CH2CH2CH2CH2CH3 (hexane), and HOCH2CH2OH (ethylene glycol) are all liquids.

Explanation:

Among the four compounds given, compound C, which is CH3CH2CH3 (also known as propane), is a gas at room temperature. Compound A (CH3CH2OH, or ethanol), compound B (CH3CH2CH2CH2CH2CH2CH3, or hexane), and compound D (HOCH2CH2OH, or ethylene glycol) are all liquids at room temperature.

The state of a compound at room temperature depends on factors like molecular mass and intermolecular forces. Propane has a smaller molecular mass and weaker intermolecular forces than the others, making it a gas at room temperature.

Learn more about States of Compounds here:

brainly.com/question/33057290

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Answer:

3. N2(g) +3H2(g)->2NH3(g)

Explanation:

Reactions can be broadly classified as endothermic and exothermic reactions. In the former, energy or heat is absorbed by the reactants and the enthalpy change of the reaction is positive. In the later, heat is released ans the enthalpy change of the reaction is negative.

For the given reactions, the enthalpy change or ΔH values are:

1. 2C(s) + 2H2(g) -> C2H4(g)        ΔH = +52.4 kJ

2. 2C(s)+3H2(g) -> C2H6(g)         ΔH = -84 kj

3. N2(g) +3H2(g)->2NH3(g)          ΔH = -91.8 kJ

4. N2(g)+O2(g) -> 2NO(g)            ΔH = +182.6 kJ

Reactions 1 and 4 are endothermic while reactions 2 and 3 are exothermic in which heat is released.

More negative the ΔH value, greater is the amount of heat released.

Thus, reaction 3, represents a change resulting in the greatest quantity of energy released

Answer:

1.33%

Explanation:

In an aqueous solution, a weak acid such as acetic acid, will be in equilibrium with its conjugate base, acetate ion, thus:

CH₃CO₂H(aq) + H₂O(l) ⇌ H₃O⁺(aq) + CH₃CO₂⁻(aq )

Where dissociation constant, ka, is defined as the ratio of concentrations of products and reactants:

Ka = 1.8x10⁻⁵ = [H₃O⁺] [CH₃CO₂⁻] / [CH₃CO₂H]

H₂O is not taken into account in the equilibrium because is a pure liquid

When a solution of acetic acid becomes to equilibrium, the original concentration of the acid decreases producing more H₃O⁺ and CH₃CO₂⁻.

The concentrations at equilibrium when a 0.100M solution of acetic acid reaches this state, is:

[CH₃CO₂H] = 0.100M - X

[H₃O⁺] = X

[CH₃CO₂⁻] = X

Where X is reaction coordinate.

Replacing in Ka expression:

1.8x10⁻⁵ = [H₃O⁺] [CH₃CO₂⁻] / [CH₃CO₂H]

1.8x10⁻⁵ = [X] [X] / [0.100M - X]

1.8x10⁻⁶ - 1.8x10⁻⁵X = X²

1.8x10⁻⁶ - 1.8x10⁻⁵X - X² = 0

Solving for X:

X = -0.00135 → False solution. There is no negative concentrations.

X = 0.00133 → Right solution.

That means concentration of acetate ion is:

[CH₃CO₂⁻] = 0.00133M.

Now, percent ionization is defined as 100 times the ratio between weak acid that is ionizated, [CH₃CO₂⁻] = 0.00133M, per initial concentration of the acid, [CH₃CO₂H] = 0.100M. Replacing:

% Ionization = 0.00133M / 0.100M × 100 =

1.33%

Answer:

radiation

LOL but also heat

Explanation:

hope this helps

Answer:

Explanation: NO, because dental varnish interferes with the bonding and setting reaction of composite resins and glass ionomer restorations the use of varnish is contraindicated with these materials.