A teacher wants to perform a classroom demonstration that illustrates both chemical and physical changes. Which
would be the best demonstration that she could use?
O bending a piece of aluminum
O breaking a matchstick
O dissolving sugar in water
O burning a candle
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Answers

Answer 1
it would be dissolving sugar in water/burning a candle
Answer 2

Answer:

d. burning a candle

Explanation:

edge 2021

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Related Questions

Help PLZ!!! Which statement accurately represents the arrangement of electrons in Bohr’s atomic model? -Electrons move around the nucleus in fixed orbits of equal levels of energy. -Electrons move around the nucleus in fixed orbits of increasing levels of energy. -Electrons move randomly in the relatively large space surrounding the nucleus. -Electrons vibrate in fixed locations around the nucleus.

Answers

Answer:

electrons move around the nucleus in fixed orbits of equal amounts of energy

Explanation:

To see the number of atoms of an element in a given molecule we need to multiply stoichiometry to the number that is written on the foot of the element that is stoichiometry. The correct option is option B.

What is atom?

Atom is the smallest particle of any element, molecule or compound. Atom can not be further divided. Atoms contains nucleus in its center and electron that revolve around the atom in fixed orbit.

In the nucleus, proton and neutron are present. Electron has -1 charge while proton has +1 charge. Neutron is neutral that is it has no charge. So overall the charge of nucleus is due to only proton, not by neutron.

According to Bohr’s atomic model,  electrons move around the nucleus in fixed orbits of increasing levels of energy.

Therefore, the correct option is option B that is electrons move around the nucleus in fixed orbits of increasing levels of energy.

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Which energy profile best shows that the enthalpy of formation of CS2 is 89.4 KJ/mol?

Answers

Answer:

Option C. Energy Profile D

Explanation:

Data obtained from the question include:

Enthalpy change ΔH = 89.4 KJ/mol.

Enthalpy change (ΔH) is simply defined as the difference between the heat of product (Hp) and the heat of reactant (Hr). Mathematically, it is expressed as:

Enthalpy change (ΔH) = Heat of product (Hp) – Heat of reactant (Hr)

ΔH = Hp – Hr

Note: If the enthalpy change (ΔH) is positive, it means that the product has a higher heat content than the reactant.

If the enthalpy change (ΔH) is negative, it means that the reactant has a higher heat content than the product.

Now, considering the question given, the enthalpy change (ΔH) is 89.4 KJ/mol and it is a positive number indicating that the heat content of the product is higher than the heat content of the reactant.

Therefore, Energy Profile D satisfy the enthalpy change (ΔH) for the formation of CS2 as it indicates that the heat content of product is higher than the heat content of the reactant.

The correct answer is Option C

For the reaction 2HNO3 + Mg(OH)2 + Mg(NO3)2 + 2H20, how many grams of magnesium
nitrate are produced from 17.37 mol of nitric acid, HNO3?
Select one:
O a. 1290
Ob. 859
O c. 5160
Od. 1080

Answers

Answer:

mass = (a) 1290

Explanation:

as 2 moles of nitric acid gives one mole of of magnesium nitrate . we should divide the number of moles of of nitric acid by 2 .

Then apply the formula:

number of moles= mass/molar ratio

thanks

Mass = A 1290 is the answer

what is the the chemical name for hydroden and oxygen​

Answers

Answer:

hydrogen peroxide is a chemical name for hydrogen and oxygen

H2O is the Answer hope this helps

Which of these is an example of how engineers have contributed to society?
A. Our current understanding of viruses
B. The theoretical mathematics describing the orbits of planets
around the sun
C. The seven-mile bridge that spans across the Gulf of Mexico to
connect two cities of the Florida Keys
D. Nomadic tribes traveling in search of food to hunt and gather

Answers

Hope this helps .. A

The diagrams show the partides of a substance
Which statement best describes the process that the diagrams show?
O A solid loses fonetic energy to become a loud and then becomes a gas
O A solid sains kinetic energy to become a loud and then becomes a gas
O Asas loses tonerc energy to become a loud and then becomes a solid
O A gas as kinetic energy to become a loud and then becomes a solid

Answers

Answer:

B. A solid gains kinetic energy to become a liquid and then becomes a gas.

Tartaric acid, C4H6O6, has the first ionization constant with the value: Ka1 = 9.20 × 10-4. Calculate the value of pKb for the conjugate base of tartaric acid. 10.963 3.036 1.087 x 10-11 9.20 x 10-4

Answers

Answer:

pKb = 10.96

Explanation:

Tartaric acid is a dyprotic acid. It reacts to water like this:

H₂Tart  +  H₂O  ⇄  H₃O⁺   +  HTart⁻         Ka1

HTart⁻  +  H₂O  ⇄  H₃O⁺   +  Tart⁻²           Ka2

When we anaylse the base, we have

Tart⁻²   +  H₂O  ⇄  OH⁻  +  HTart⁻       Kb1

HTart⁻  +  H₂O  ⇄  OH⁻  +    H₂Tart          Kb2

Remember that Ka1 . Kb2  = Kw, plus pKa1 + pKb2 = 14

Kb2 = Kw / Ka1  →   1×10⁻¹⁴ / 9.20×10⁻⁴  = 1.08×10⁻¹¹

so pKb = - log Kb2   → - log 1.08×10⁻¹¹ = 10.96  

Calculate the number of g of KCN that will react with 1.06 mol of HCl.

Answers

Answer:

68.9 g of KCN.

Explanation:

We'll begin by writing the balanced equation for the reaction. This is given below:

KCN + HCl → KCl + HCN

From the balanced equation above,

1 mole of KCN reacted with 1 mole of HCl.

Next, determination of the number of mole of KCN needed to react with 1.06 moles HCl.

This is illustrated below:

From the balanced equation above,

1 mole of KCN reacted with 1 mole of HCl.

Therefore, 1.06 moles of KCN will also react with 1.06 moles of HCl.

Finally, we shall convert 1.06 moles of KCN to grams.

This can be obtained as follow:

Molar mass of KCN = 39 + 12 + 14 = 65 g/mol.

Mole of KCN = 1.06 moles

Mass of KCN =...?

Mole = mass /Molar mass

1.06 = mass of KCN / 65

Cross multiply

Mass of KCN = 1.06 x 65

Mass of KCN = 68.9 g

Therefore, 68.9 g of KCN is needed to react with 1.06 moles of HCl.

Which statement best describes how energy is important to chemistry?
A. Energy is stored in an atom's electrons.
B. Energy is not conserved during chemical reactions,
C. Energy is absorbed and released during chemical reactions,
D. Energy holds atoms and bonds together,

Answers

Answer:

C. Energy is absorbed and released during chemical reactions,

Explanation:

All chemical reactions involve energy. Energy is used to break bonds in reactants, and energy is released when new bonds form in products. Endothermic reactions absorb energy, and exothermic reactions release energy.

Call dioxide energy holds atoms in bonds together energy is absorbed and released during chemical reactions energy is not conserved during chemical reactions energy is stored in autumn selections

Why is warm honey easier to pour than cold honey?

A) Increasing the temperature breaks the molecules down into atoms, which are smaller.

B) Increasing the temperature increases the kinetic energy of the molecules, which makes it easier to overcome the attractive forces between molecules.

C) Increasing the temperature converts the sugars into water, which flows easier.

D) Increasing the temperature makes the honey more viscous.

Answers

C

Explanation:

Warm honey is easier to pour because the molecules or what we call as atoms are tightly packed in solids and when solids convert into liquid they flow easily.I HOPE YOU MIGHT FIND THIS VERY HELPFULLWITH LOVE FAULTYDEVILLOVE YA......

warm honey easier to pour than cold honey due to Increasing the temperature converts the sugars into water, which flows easier.

What are the components of honey ?

Honey contains sugar,  water  and other ingredients, where Sugar gives  gives sweetness, water maintain fluidity, and other components are present in a least amount and the differences are the color, aroma and taste.

Three types of sugar such as fructose (41%), grape sugar  or glucose about 34%  and sucrose contain 1 and 2%, other components include  minerals, proteins, acids and undetermined matter.

Minerals constitute 3.68%, increase the value of honey for human consumption and the most common minerals are potassium, chlorine, sulfur, calcium, sodium, phosphorus, magnesium, silicon, iron, manganese and copper.

Proteins are collected from nectar and pollen  which is the integral parts of plants, acids are also the component,  vitamn C and some B complex vitamins  such as riboflavin, pantothenic acid, pyridoxine, biotin, nicotinic acid are present.

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