All categories

3 years ago

Most of the mass of an atom is contained in its _____. A. electrons B. protons C. nucleus D. neutrons

1 answer:

3 0

Atom is made up of NUCLEUS and electrons revolving around nucleus.

Nucleus itself contains protons and neutrons. Protons and neutrons are approximately 1680 times heavier than the electrons. So the major contribution to the mass of an atom comes from the nucleus.

Answer is C.

You might be interested in

Q 9.3: how many triplets would you expect to observe in the 1h nmr spectra for o-chlorotoluene

agasfer [191]

Hello!

You would expect to observe 2 triplets in the ¹H NMR spectra for o-chlorotoluene.

Multiplicity observed in ¹H NMR spectra when the atom couples with a neighbor ¹H atom. The multiplicity is equal to N+1 where N is the number of neighbor atoms.

To observe a triplet, you'll need a molecule with 2 neighbor atoms. In o-chlorotoluene (shown in the figure), only protons C and D have 2 neighbor atoms (B and D; A and C, respectively), so you'll expect to see a 2 triplets.

Have a nice day!

3 0

4 years ago

Read 2 more answers

A solution of cough syrup contains 5.00% active ingredient by volume. If the total volume of the bottle is 11.0 mL , how many mi

Marta_Voda [28]

All you need to do is change 5% into a decimal which would be 5/100 = .05
then multiply the decimal by the total volume to get the amount of active ingredients in ml
.05 * 56ml = 2.8 ml of active ingredient.

Hope that helps!

4 0

3 years ago

Read 2 more answers

A sample of gas has a pressure of 100.0 KPa and 25C. Calculate the pressure if the temperature is changed to 125C while the volu

atroni [7]

Answer:

133.56kPa

Explanation:

Applying Pressure Law,

P/T = P'/T'....................... Equation 1

Where P = Initial pressure, T = Initial Temperature, P' = Final pressure, T' = Final Temperature.

From the question, we were asked to calculate P'

There, we make P' the subject of the equation

P' = PT'/T...................... Equation 2

Given: P = 100kPa, T = 25°C = (273+25) = 298K, T' = 125°C = (273+1250K = 398 K

Substitute these values into equation 2

P' = (100×398)/298

P' = 133.56kPa

Hence the pressure is 133.56kPa

6 0

3 years ago

What is the net ionic equation of the reaction below?

faltersainse [42]

Answer:

Net ionic equation:

Ca⁺²(aq) + CO²⁻₃(aq) → CaCO₃(s)

Explanation:

Chemical equation:

K₂CO₃ + CaCl₂ → KCl + CaCO₃

Balance chemical equation:

K₂CO₃(aq) + CaCl₂(aq) → 2KCl(aq) + CaCO₃(s)

Ionic equation:

2K⁺(aq) + CO²⁻₃(aq) + Ca⁺²(aq) + 2Cl⁻(aq) → 2K⁺(aq) + 2Cl⁻(aq) + CaCO₃(s)

Net ionic equation:

CO²⁻₃(aq) + Ca⁺²(aq) → CaCO₃(s)

The K⁺(aq) and Cl⁻ (aq) are spectator ions that's why these are not written in net ionic equation. The CaCO₃ can not be splitted into ions because it is present in solid form.

Spectator ions:

These ions are same in both side of chemical reaction. These ions are cancel out. Their presence can not effect the equilibrium of reaction that's why these ions are omitted in net ionic equatio n.

6 0

3 years ago

When production first began some eighty years ago, ammonia production relied upon the direct reaction between gaseous hydrogen a

kondaur [170]

Answer:

Option 2. Produce more ammonia.

Explanation:

The influence of temperature in equilibrium reactions can be predicted from the heat (enthalpy) information.

This is the chemical reaction:

3 H₂ (g) + N₂(g) ⇄ 2 NH₃(g) ∆H = −92.2 kJ

The information about the enthalpy of the reaction, ∆H = − 92.2 kJ, indicates that energy (heat) has been released to the surroundings (the products of the forward reaction have less energy than the reactants), which is defined as an exothermic reaction.

Then, you can rewrite the equaition in the form:

3 H₂ (g) + N₂(g) ⇄ 2 NH₃(g) + 92.2 kJ

This is, the heat can be seen as a product of the direct reaction (or a reactant of the reverse reaction).

Now, it is quite straight to apply Le Chatelier's principle:

a) Decreasing temperature is equivalent to extract heat or having less heat on the left side.

b) Then, the equilibrium must shift in a way that this lack of heat is compensated. Then, the reaction will shift to the right to produce more heat.

As conclusion, you can tell that in exothermic reactions, a decrase in temperature will cause the equilibrium to shift to the right.

This shift, of course, means the production of more ammonia.

The other choices are discarded following this brief reasoning:

1. increase the velocity of the gas molecules: the average velocity of the particles increases when the average kinetic energy increases, and the average kinetic energy will decrease if the temperature decreases. So, this statement is false.

3. increase the kinetic energy of the gas molecules: no, the average kinetic energy is proportional to the temperature, then reducing the temperature decreasese the average kinetic energy.

4. produce less ammonia: it was shown that reducing the temperature will produce more ammonia.

5. have no effect: no, it does have effect, as shown.

6 0

3 years ago