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3 years ago

16. As he developed his periodic table, Mendeleev grouped the elements lithium,

Chemistry

1 answer:

Aleonysh [2.5K]3 years ago

8 0

Answer:

the reactivity and the valence electrons

Explanation:

the reactivity of the elements would have played a significant role in why such elements were grouped together. the number of valence electrons dictates how reactive an element is - the less valence electrons the more reactive it is. the column, group 1 in which these elements are put together in, show that each of the elements have 1 valence electrons and are therefore reactive.

you can go on to further explain what valence electrons are, explain what the group numbers are associated with the valence electrons and how valence electrons effect reactivity. further this, talk about how the three elements have the same number of valence electrons and therefore were grouped together

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How did democtitis define atom?

klemol [59]

Democritus, theorized that atoms were specific to the material which they composed. In addition, Democritus believed that the atoms differed in size and shape, were in constant motion in a void, collided with each other; and during these collisions, could rebound or stick together.

Explanation:

One of the main atomic theorists was Democritus, a Greek philosopher who lived in the fifth century BC. Democritus realized that if a stone was partitioned fifty-fifty, the two parts would have indistinguishable properties from the whole.
Therefore, he contemplated that if the stone were to be constantly cut into littler and littler pieces at that point; sooner or later, there would be a piece that would be so little as to be inseparable. He called these small pieces of matter as "atomos", the Greek word for inseparable.

Democritus estimated that atoms were explicit to the material which they made. Also, Democritus accepted that the particles varied in size, were an inconsistent shape, crashed into one another; and during these impacts, could bounce back or stay together. Hence, changes in the matter were a consequence of separations or mixes of the atoms as they moved all through the void.

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3 years ago

20 N force moving a box to 30 meters distance. How much work id done? if it takes 10 sec to do this work, how much power is used

dalvyx [7]

Answer:

Work done = 600 J

Power used = 60 W

Explanation:

Given:

Force acting on the box is, $F=20\ N$

Displacement of the box is, $S=30\ m$

Time taken for the work, $t=10\ s$

Now, we know that, work is said to be done by a force only when there is displacement caused by the force in its direction.

Here, the force acting on the box causes a displacement of 30 m in its direction. So, work done is equal to the product of force and displacement caused.

Therefore, work done on the box is given as:

$Work=Force\times Displacement\\Work=F\times S\\Work=(20\ N)\times (30\ m)\\Work=600\ J$

Therefore, the work done is 600 J.

Now, we know that, power is given as work done per unit time.

So, power used is given as:

$Power=\frac{Work}{Time}\\\\Power=\frac{600\ J}{10\ s}\\\\Power=60\ W$

Therefore, the power used is 60 W.

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3 years ago

4. Energy can be conserved by -

mart [117]

Energy can be conserved by efficient energy use.

Answer: Option A

Explanation:

Energy can be transferred from one form to another, but it cannot be destroyed or created. So it can be conserved if efficiently used. Thus efficient usage of energy lead to conservation of energy. Due to conservation of energy, the forces can be renewable and non-renewable.

So, we should know how the input energy can be completely converted to another form of energy leading to efficient usage of energy without any loss. As if there is no loss, input energy will be equal to output energy leading to 100% efficiency.

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3 years ago

Nuclear energy is the heat energy produced during controlled splitting, or ________ , of radioactive isotopes

erma4kov [3.2K]

Answer is: nuclear fission.
Nuclear fission is radioactive decay process in which the nucleus of an atom splits into smaller parts. In this process produces free neutrons and gamma photons and releases a very large amount of energy.
Nuclear fission produces energy for nuclear power and nuclear weapons.

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3 years ago

This man is using a block and tackle to lift a heavy bale of cotton. the block and tackle contains which simple machine?

AlladinOne [14]

The simple machine used is called atwood machine.

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3 years ago