A physical change is __________ if energy is given off.Select one:
a. exothermic
b. endothermic
c. a chemical change
d. not possible

Answers

Answer 1
Answer:

Answer:

A

Explanation:


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In the following reaction 2C6H6 + 15O2 12CO2 + 6H2O how many grams of oxygen will react with 10.47 grams of benzene (C6H6)?
In general, the solubility of ________ in water decreases as temperature increases.
Consider a neatly packed box of marbles compared to what you get if you dump the marbles on the floor. Which state has the higher entropy. a. spilled marbles b. marbles in packed box c. none d. both
What term describes an atom's tendency to hold on on to electrons?
One atom of silicon can properly be combined in a compound witha. three atoms of hydrogen.b. four atoms of calcium.c. two atoms of oxygen.d. one atom of chlorine.

There are three stable atoms of Argon (Atomic Number 18): Argon-36, Argon-38 andArgon-40. What would the atoms of these isotopes have in common? What would
be different about their atoms? (4 points)
HELP ASAP

Answers

On the periodic table, argon has an average atomic weight of 39.948 amu. This number is really near 40. This suggests that Ar-40 is the isotope of argon (Ar) that is most prevalent in the natural world.

What characteristics do argon-36, argon-38, and argon-40 share?

If all three argon atoms are neutral, they would each contain 18 protons and 18 electrons. In comparison to one another, the three isotopes will each have a distinct number of neutrons (18, 20, and 22 neutrons respectively).

Why is potassium a 39 positioned before argon, atomic number 40, in the current periodic table?

Atomic number, not atomic mass, is used to categorise the elements. As the atomic number of argon (18) is less than that of potassium (19)

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When an excited electron in a hydrogen atom falls from ????=5 to ????=2, a photon of blue light is emitted. If an excited electron in an He+ ion falls from ????=4, which energy level must it fall to (????1) for blue light of a similar wavelength to be emitted?

Answers

Final answer:

Blue light is emitted when an electron in a He+ ion falls from the energy level n=4 to n=1. This is because the energy difference between these levels is similar to that in a hydrogen atom when blue light is emitted (from n=5 to n=2).

Explanation:

The energy of the emitted photon when an electron transitions between energy levels in an atom is determined by the difference between the energy levels it transitions between. This is described by the formula: E = hν, where E stands for energy, h stands for Planck's constant, and ν stands for frequency. The color of the emitted light, or the wavelength, is determined by the energy of the photon.

For blue light to be emitted when an excited electron falls from n=4 in a He+ ion, it must fall into n=1. This is because the energy gap between the n=4 and n=1 levels in a He+ ion is similar to that between the n=5 and n=2 levels in a hydrogen atom, which results in the emission of blue light.

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Final answer:

In a helium ion (He+), an electron would need to fall from n=4 to n=1 to emit a photon of blue light, similar to the photon emitted when an electron in a hydrogen atom falls from n=5 to n=2.

Explanation:

According to the Bohr model of atoms, when an electron falls from a higher to a lower energy level, a photon is emitted. The energy (and therefore color) of the photon corresponds to the energy difference between the two energy levels. In the case of your question, an excited electron in a hydrogen atom falls from n=5 to n=2 and emits a photon of blue light.

If an electron in an excited helium ion (He+) falls from the n=4 level, to emit a photon of similar energy (and thus color), it must fall to a level that yields a similar energy difference. Based on the energy levels of helium and hydrogen, the electron in the He+ ion would need to fall to n=1 to emit a photon of similar energy to the blue light from the hydrogen atom, given that the energy difference in He+ ion is larger than in hydrogen atom for the same quantum numbers due to its greater nuclear charge.

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Which of the following bonds is the most polar in nature:(1) Cl2
(2) HCl
(3) HBr
(4) HI

Answers

The answer will be (4) HI because the greater the difference of the bonds in electronegativity, the more polar a bond is.

Final answer:

HCl is the most polar bond, as greater the difference in electronegativity, the more polar the bond. Here, Chlorine is more electronegative than Hydrogen, Bromine, and Iodine, making the HCl bond most polar.

Explanation:

The most polar bond in the list provided is HCl. Polarity in bonds is determined by the difference in electronegativity between the two atoms in the bond. The greater the electronegativity difference, the more polar the bond. Chlorine (Cl) is more electronegative than Hydrogen (H), Bromine (Br), and Iodine (I), and so the bond between Cl and H is the most polar. The other three options (Cl2, HBr, HI) are either bonds between atoms of the same element (and therefore nonpolar because the electrons are shared equally) or are less polar due to the lower electronegativity difference.

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Please help with this.

Answers

1. Double-Replacement reactions

2. Decomposition  

3. Combustion

4. Syntesis

5. Single replacement

Further explanation

Given

Chemical equations

Required

Type of reaction

Solution

1. 2AgNO₃ + MgCl₂ ⇒ 2AgCl + Mg(NO₃)₂

Double-Replacement reactions. Happens if there is an ion exchange between two ion compounds in the reactant

2. 2KBr⇒2K +Br₂

Decomposition  

Single compound breaks down in to 2 or more products

3. C₃H₈ + 5O₂ ⇒ 4H₂O + 3CO₂

Combustion

Hydrocarbon and Oxygen reaction and form water and carbon dioxide

4. NaO + H₂O ⇒ NaOH

Syntesis

2 or more reactants combine to form a single product

5. Zn + CuCl₂ ⇒ZnCl₂ + Cu

Single replacement

One element replaces another element from a compound

Gasoline is a mixture composed primarily of hydrocarbons such as isooctane, which is also known as 2,2,4-trimethylpentane.Gasoline is assigned a number called an octane rating. Gasoline with an octane rating of 87 performs the same as a mixture that consists of 87% isooctane and 13% heptane.
An alternative fuel, E-85, can be used in some automobiles. This fuel is a mixture of 85% ethanol and 15% gasoline.

State the octane rating of a gasoline sample that performs the same as a mixture consisting of 92% isooctane and 8% heptane.
Identify the functional group in a molecule of ethanol in the alternative fuel E-85.

Answers

Because of the 92% isooctane, the gasoline sample's octane rating is 92.The functional group in ethanol is the hydroxyl group.

3.3 kg aluminum chromate

Answers

this is not a question