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3 years ago

Select the true statement:

Chemistry

1 answer:

Vsevolod [243]3 years ago

8 0

Answer:

Bonds are broken and new bonds are formed during chemical reactions only.

Explanation:

A physical change in a substance doesn't change what the substance is.

In a chemical change where there is a chemical reaction, a new substance is formed and energy is either given off or absorbed.

Physical changes can be reversed, chemical changes cannot be reversed with the substance changed back without extraordinary means, if at all. For example, a cup of water can be frozen when cooled and then can be returned to a liquid form when heated.

So, the right choice is:

Bonds are broken and new bonds are formed during chemical reactions only.

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What is the law of conservation?

frez [133]

Answer:In physics, a conservation law states that a particular measurable property of an isolated physical system does not change as the system evolves over time. Exact conservation laws include conservation of energy, conservation of linear momentum, conservation of angular momentum, and conservation of electric charge. Wikipedia

Explanation:

7 0

3 years ago

in an experiment 3.425g of lead oxide was reduced to form 3.105g of lead the empirical formula of the lead oxide is?

Romashka-Z-Leto [24]

Answer:

Pb3O4

Explanation:

According to this question, 3.425g of lead oxide was reduced to form 3.105g of lead in an experiment. Since lead oxide contains both lead (Pb) and oxygen (O) element,

Mass of lead oxide = 3.425g

Mass of lead = 3.105g

Mass of oxygen = (3.425g - 3.105g) = 0.320g

Next, we convert each mass value to mole by dividing by respective molar mass

Pb = 3.105g ÷ 207.2 = 0.0149mol

O = 0.320g ÷ 16 = 0.02mol

Next, we divide each mole value by the smallest (0.0149)

Pb = 0.0149mol ÷ 0.0149mol = 1

O = 0.02mol ÷ 0.0149mol = 1.342

Multiply each ratio value by 3 to get:

Pb = 1 × 3 = 3

O = 1.342 × 3 = 4.026

The whole number ratio, approximately, of Pb and O is 3:4, hence, their empirical formula is Pb3O4.

4 0

2 years ago

Óxido cuprico+amoniaco-------Nitrógeno +cobre +agua(redox)

tigry1 [53]

Answer:

?? no entiendo la pregunta?...pero gracias por los puntos free UvU

Explanation:

3 0

3 years ago

What materials are going to use to measure for your data?

BaLLatris [955]

Answer:

a small unit of measurement used for measuring data is bit.

4 0

3 years ago

1 message Which process results in the increase in entropy of the universe? the cooling of a hot cup of coffee in room temperatu

andreyandreev [35.5K]

Answer:

Melting of snow

Evaporation of water from desk

Explanation:

Processes that increase the entropy of the universe are those processes that have an increased disorderliness. We should note that there are three principal states of matter which are the liquid, gas and solid. The gaseous state is the most disorderly while the solid is the least disorderly.

Now. We can see that the cooling of a hot cup of coffee is a process that needs or leads to a loss in temperature which obviously decreases disorderliness of the universe.

The melting of snow however is a process that leads to an increase in the disorderliness of the universe. It entails moving from the solid state to the liquid state. It tends to move to a more disordered state indicating an increase in the entropy of the universe.

The evaporation of water from the desk is quite similar to that above. Hence since we are moving from the liquid to the gaseous state via evaporation, we can state that the entropy of the universe has increased since we have moved from a state with a lesser degree of disorderliness to a state that is more disordered I.e from liquid to gaseous state.

3 0

3 years ago