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3 years ago

True or false A(n) rift valley forms where plates diverge on land.

Chemistry

2 answers:

motikmotik3 years ago

4 0

Answer:

True

Explanation:

vlabodo [156]3 years ago

3 0

Answer:

true

Explanation:

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Which term "causes an object to change motion?"

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Answer:

force

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3 years ago

Explain how the symbols of the elements were devised?

Ronch [10]

Answer: The chemical elements are made of atoms. Half of Dalton's symbols used letters inside a circle to represent the elements. Berzelius organized 47 elements with letters alone, and he based those letters not primarily on the English names, but on the Latin ones. Also Most of them have their first-second letter on them

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Stage in a star's evolution formed as the core of a main sequence star uses up its helium and the outer layers escape into space

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3 years ago

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Consider separate samples of water and carbon dioxide, each with the same mass. Which contains the greater number of molecules?

Ahat [919]

Answer: The sample that contains the greater number of molecules is water.

Explanation: To calculate the number of molecules, it is used the Avogadro's number ( $6.02*10^{23}$ particles/molecules). So, considering that the mass to water and carbon dioxide is 1g (it can be any other number), the relationship between moles and molar weight is:

$moles =\frac{mass}{molar weight}$

To water: $moles = \frac{1g}{18 g/mol}$ = 0.05 moles.

Therefore,

1 mol ---- $6.02*10^{23}$ molecules

0.05 moles ---- x

x = $0.30*10^{23}$ molecules of water.

To carbon dioxide: $moles = \frac{1g}{44 g/mol}$ = 0.02 moles.

Therefore,

1 mol ---- $6.02*10^{23}$ molecules

0.02 moles ---- y

y = $0.12*10^{23}$ molecules of carbon dioxide.

7 0

3 years ago

Which reactants would lead to a spontaneous reaction?

balandron [24]

Answer: Option (b) is the correct answer.

Explanation:

The elements which have excess or deficiency of electrons will react readily.

Atomic number of Mn is 25 and electronic configuration of $Mn^{2+}$ is [Ar] $4s^{0}3d^{5}$ . This configuration is stable.

Atomic number of Cr is 24 and electronic configuration of $Cr$ is [Ar] $4s^{1}3d^{5}$ . This configuration is not stable.

Atomic number of Fe is 26 and electronic configuration of $Fe$ is [Ar] $4s^{2}3d^{6}$ . This configuration is stable.

Atomic number of Cu is 29 and electronic configuration of $Cu^{2+}$ is [Ar] $4s^{0}3d^{9}$ . This configuration is not stable.

Atomic number of Al is 13 and electronic configuration of Al is $1s^{2}2s^{2}2p^{6}3s^{2}3p^{1}$ . This configuration is not stable.

Atomic number of Ba is 56 and electronic configuration of $Ba^{2+}$ is [Kr] $4d^{10}5s^{2}5p^{6}$ . This configuration is stable.

Atomic number of Mg is 12 and electronic configuration of $Mg^{2+}$ is $1s^{2}2s^{2}2p^{6}$ . This configuration is stable.

Atomic number of Sn is 50 and electronic configuration of Sn is [Kr] $4d^{10}5s^{2}5p^{2}$ . This configuration is stable.

Thus, we can conclude that out of the given options, only Fe and $Cu^{2+}$ reactants would lead to a spontaneous reaction as they have incomplete sub-shells. Therefore, in order to gain stability they will readily react.

8 0

3 years ago