Which of the following describes a chemical change?

Which is a nonmetal ? 1. Sodium (Na) 2.lithium(Li) 3. Calcium (ca) 4. Carbon(c)

Savatey [412]

Answer: Calcium (ca)

Explanation:

3 0

3 years ago

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What is the oxidation state of each element in the compound CaS04? Include +or - in your answer as appropriate

borishaifa [10]

Answer:therefore the oxidation state of sulphur is +6 in the compound CaSO4.

Explanation:

5 0

3 years ago

N the reaction Mg + 2HCl -> MgCl2 + H2 which element’s oxidation number does not change?

BartSMP [9]

Answer:- Oxidation number of Cl does not change as it is -1 on both sides.

Explanations:- oxidation number of Mg on reactant side is 0 as it is in its elemental form(not combined with another element).

Oxidation number of hydrogen in its compounds is +1, so if H is +1 in HCl the oxidation number of Cl is -1 as the sum has to be zero.

On product side, Mg oxidation number is +2 as the oxidation number of alkaline earth metals in their compounds is +2.

Two Cl are present in magnesium chloride, so if Mg is +2 then Cl is -1.

Oxidation number of H on product side is 0 as it is present in its elemental for, $H_2$ ,

So, it is only chlorine(Cl) whose oxidation number does not change for the given equation.

4 0

3 years ago

What is the specific latent heat of a fussion for a substance that takes 550 kj to melt 14 kg at 262 k?

Lina20 [59]

The latent heat is correlated with energy as follows:

Q = mL

550 * 103 = 14 * 103 * L

L = 39.285 J /g

Thus, latent heat of the substance is 39.285 j /g

7 0

3 years ago

Drag each item to indicate whether it is related to Aristotle's or Ptolemy's model of the solar system, or to both. Some items m

Romashka-Z-Leto [24]

Answer:

Aristotle's Model :

geocentric

planets fixed on nested spheres

Ptolemy's model:

geocentric

planets fixed on epicycles

accurately predicted the positions of the planets

Explanation:

Let's begin by the fact both models are geocentric and make a brief explanation of them:

Aristotle's Model :

Aristotle built his model based on observations and philosophical assumptions, not on measurements or calculations, then he mistakenly thought the Earth was the center of the universe.

So, according to this model, the universe was spherical and finite, with the Earth immobile at its center, composed of the four fundamental elements (made up of spherical layers): ground, water, air and fire; and the Sun along with the fixed planets in their respective concentric spheres (also called nested spheres) revolving around the Earth.

Ptolemy's model:

Ptolemy's model of the universe was also geocentric, placing the Earth motionless in the center of the known universe and was the accepted model for a long time during the Middle Ages.

In this sense, ccording to Ptolemy's model of the universe our planet remains stationary while the other planets, the Moon and the Sun describe complicated orbits around it (called epicycles).

However, this model predicted with an acceptable accuracy for that time the motion of the known planets, until Copernicus appeared with the revolutionary Heliocentric model.

5 0

3 years ago