Which of the following statements describes all
exothermic reactions?
A. Exothermic reactions form gases.
B. Exothermic reactions require a catalyst.
C. The energy of the reactants is lower than the
energy of the products,
D. The energy of the reactants is higher than the
energy of the products.

Answer:

hydrogen ion dissolve in water is acid and hydroxide ion dissolve in water is basi

the recation in which oxidation and reduction goes side by side is redox redaction

The correct answer is C. Zn²+. In a magnesium and zinc galvanic cell, the anode is the magnesium (Mg(s)) and the cathode is the zinc (Zn²+).

A zinc galvanic cell is an electrochemical device that uses a zinc anode and a cathode of a different material, usually copper, to produce electricity. The reaction that occurs in the cell is a redox reaction, which involves the oxidation of zinc at the anode and the reduction of copper at the cathode.

Zn²+. In a magnesium and zinc galvanic cell, the anode is the magnesium (Mg(s)) and the cathode is the zinc (Zn²+). In this cell, the magnesium metal is oxidized to form Mg2+ ions which are released into the solution. The zinc ions (Zn²+) are then reduced to zinc metal (Zn(s)) at the cathode.

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Answer: B

Explanation:

Answer:

Because Polar regions get less of the sun's direct rays, they are the coldest climates on Earth.

Explanation:

Answer:

70.0 %

Explanation:

Step 1: Given data

Step 2: Calculate the mass of oxygen (mO) in the compound

The mass of the compound is equal to the sum of the masses of the elements that form it.

mNxOy = mN + mO

mO = mNxOy - mN

mO = 250 g - 74.66 g = 175 g

Step 3: Determine the percent composition of oxygen in the sample

We will use the following expression.

%O = mO / mNxOy × 100%

%O = 175 g / 250 g × 100% = 70.0 %

Answer:

the answer to this is 71.0 grams of chlorine

Answer:

Uranium experiences a stronger net force holding its protons and neutrons together than barium.

Explanation:

Answer:

The answer is 1. acid-base

Explanation:

This is pretty self-explanatory, when an acid and base react, it is called an acid-base reaction. Redox reactions are where two reactants exchange electrons, precipitation reaction is where a solid is formed, and combustion reaction is where a compound is reacted with oxygen so none of those can be the answer.

Answer:

298.9 million years ago - 251.902  million years ago

Explanation:

It might be in the 2011 Earth Science Review Packet so maybe go check that out

Answer:

THE CORRECT ANWER IS ;Cells make up tissues, tissues make up organs, and organs make up organ ... All the systems of the body work together to keep an organism up and running. ... out a particular function, and groups of organs with related functions make up the ... Connective tissue supports and, as the name suggests, connects other tissues.

Explanation:

Answer: The correct answer to this question is "a tissue.

Explanation: "Tissue is a term used to describe a group of cells that have similar structure and function and work together to carry out a specific function in the body of a plant or animal.For example, muscle tissue is made up of muscle cells that work together to help the body move, while nervous tissue is made up of nerve cells that transmit signals throughout the body.An organism is a living entity that can carry out all of the basic life processes, while photosynthesis is the process by which plants use sunlight, carbon dioxide, and water to produce food in the form of glucose.

The mass of hexane, C₆H₁₄ that would be needed to produce 562 grams of carbon dioxide, CO2 is 183 g

We'll begin by writing the balanced equation for the reaction.

2C₆H₁₄ + 19O₂ → 12CO₂ + 14H₂O

From the balanced equation above,

528 g CO₂ were produced from 172 g of C₆H₁₄

With the above information, we shall determine the mass of hexane, C₆H₁₄ needed to produce 562 g CO₂. Details below:

From the balanced equation above,

528 g CO₂ were produced from 172 g of C₆H₁₄

Therefore,

562 g of CO₂ will react to produce = (562 × 172) / 528 = 183 g of C₆H₁₄

Thus, the mass of hexane, C₆H₁₄ needed is 183 g

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Answer:

a. True

Explanation:

Methyl red is an indicator widely used in quality control of oxides as Zinc oxide in the titration with sulfuric acid.

As is used in titrations of acid-base reactions the indicator change in colour. Is red when the pH < 4.4 (Acidic Solutions) and is yellow when pH > 6.2 (Neutral-Basic solutions).

A change in colour means the structure of the indicator is changing with pH. Thus, the answer is:

Answer:

answer is c

Allele is a variant form of a gene. Some genes have a variety of different forms, which are located at the same position, or genetic locus, on a chromosome. Humans are called diploid organisms because they have two alleles at each genetic locus, with one allele inherited from each parent.

Answer:

A or C

Explanation:

I don't know if I'm correct but I think it's A or C you don't have to choose them.

Answer:

3.1x10²³

Explanation:

I'm going to answer the question assuming the number of molecules of FeCl₃ is asked, rather than the number of atoms.

First we convert 9.3x10²³ atoms of HCl into moles of HCl, using Avogadro's number:

Then we convert 1.54 moles of HCl into moles of FeCl₃, using the stoichiometric coefficients of the reaction:

Finally we calculate how many FeCl₃ molecules are there in 0.51 moles:

The closest option is 3.1x10²³.

The number of atoms produced is four times the number of FeCl₃ molecules produced.

Answer:

The ideal gas law is a formula that relates the pressure, volume, temperature, and number of moles of a gas. It can be expressed as:

PV = nRT

where P is the pressure of the gas, V is the volume of the gas, n is the number of moles of the gas, R is the gas constant, and T is the temperature in Kelvin.

Since the number of moles and the temperature are constant in this problem, we can rearrange the formula to solve for the pressure:

P = (nRT) / V

Plugging in the known values, we get:

P = (nRT) / V

= (n * R * (35 + 273)) / 0.25 L

= (n * R * 308 K) / 0.25 L

We are given that the pressure is 500 mmHg and the volume is 0.25 L at this pressure, so we can set these equal:

500 mmHg = (n * R * 308 K) / 0.25 L

Solving for n, we get:

n = (500 mmHg * 0.25 L) / (R * 308 K)

We know that the pressure and volume of the gas at its original state are what we are trying to solve for. Let's call the original pressure P_0 and the original volume V_0. We can then express the relationship between the original and final state of the gas as:

P_0 * V_0 = n * R * T

Substituting the expression we found for n and the known values, we get:

P_0 * V_0 = ((500 mmHg * 0.25 L) / (R * 308 K)) * R * 308 K

Solving for P_0, we get:

P_0 = (500 mmHg * 0.25 L) / (R * 308 K) * (R * 308 K) / V_0

= (500 mmHg * 0.25 L) / (V_0)

Since V_0 = 0.5 L, we can substitute this value to get:

P_0 = (500 mmHg * 0.25 L) / (0.5 L)

= 500 mmHg / 2

= 250 mmHg

Therefore, the original pressure of the gas was 250 mmHg.

Answer:

Explanation:

Standard enthalpy of combustion (ΔH∘C) is the enthalpy change when 1 mole of a substance burns under standard state conditions;

All of the ions in groupings 16 and 17 of nonmetals have a charge of -1. Spontaneous non-metals include brittle both thermally & electrically insensitive compounds.

Non-metals are elements that frequently gain electrons during chemical processes to generate anions. These substances are electronegative ones. They lack luster, are fragile, and are poor heat- and electricity-conductors (except graphite). Non-metals come in solid, liquid, or gaseous forms.

Lithium, Beryllium, Sodium, Mg, Aluminum, Potassium, & Calcium are the minerals within the first twenty elements. Hydrocarbons, Helium, Carbo, Nitrogen, Oxygen, Hydrochloric acid, Neon, Phosphorous, Sulphur, Chlorinated, and Argon now comprise the non-metals that comprise the first twenty elements.

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Answer:

The molar mass of the gas is 99.4 g/mol

Explanation:

Ideal gas law PV=nRT. P=155.3 T=127+273= 400K V=25.0 Gas constant=8.314 Now substiture the values into the equation n=PV/RT

n= (155.5kPa x 25.0mL x 1l/1000mL)/ 8.312l*KPa/mol*K x 400K

n= 0.001167 mol

Molar mass= Mass/ Number of moles

                = 0.116g /0.001167 mol

                = 99.4 g/mol

Answer:

increasing to decreasing:

F--- S--- Al--- Na--- K

not sure...

Thermal energy is the sum of all the potential and kinetic energy of the atoms within a system that is responsible for its temperature.

Friction transforms other forms of energy into thermal energy. Atoms are the building blocks of matter. Atoms are composed of subatomic particles called protons, neutrons, and electrons.Periodic trends are patterns on the periodic table that illustrate elements’ characteristics.Significant trends are atomic radius, metallic reactivity, electronegativity, electron affinity, and ionization energy.

Atomic radius and metallic reactivity trends: They increase when they move down a group and left across a period.Electronegativity, electron affinity, and Ionization energy trends: They increase when they move up a group and right across a period.

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Answer:

Oxygen has 8 protons in the nucleus while nitrogen only has 7. A bonding pair will experience more attraction from the oxygen's nucleus than from nitrogen's, and so the electronegativity of oxygen is greater.

the answer is that it is a

Answer: There are [tex]5.42 \times 10^{23}[/tex] [tex]Ca^{2+}[/tex] ions present in 0.9 mol of [tex]CaCl_{2}[/tex].

Explanation:

According to the mole concept, there are [tex]6.022 \times 10^{23}[/tex] atoms present in one mole of a substance.

As here, 0.9 mol of [tex]CaCl_{2}[/tex] are present. Also, there is only one atom of Ca is present in a molecule of [tex]CaCl_{2}[/tex].

Hence, calcium ions present in 0.9 mol of [tex]CaCl_{2}[/tex] are calculated as follows.

[tex]No. of ions = 1 \times 0.9 \times 6.022 \times 10^{23}\\= 5.42 \times 10^{23}[/tex]

Thus, we can conclude that there are [tex]5.42 \times 10^{23}[/tex] [tex]Ca^{2+}[/tex] ions present in 0.9 mol of [tex]CaCl_{2}[/tex].

Answer:  Blood alcohol levels at autopsy are valid up to 48 hours after death when simple principles are observed in the collection and storage of samples. Alcohol levels in samples of blood taken from the intact heart are as significant as levels of blood from the femoral veins.

Explanation:

Answer:

If the victim was submerged in water

Explanation:

A buffer solution is one in which the pH of the solution is "resistant" to small additions of either a strong acid or strong base. Buffers usually consist of a weak acid and its conjugate base, in relatively equal and "large" quantities. Calculations are based on the equation for the ionization of the weak acid in water forming the hydronium ion and the conjugate base of the acid. "HA" represents any weak acid and "A-" represents the conjugate base.

HA(aq) + H2O(l) --> H3O+(aq) + A-(aq)

Ka = [H3O+][A-]

Answer:

I think first molar mass of ch3o which is 31

Explanation: