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2 years ago

ANSWER THESE 5 MULTPLE CHOICE QUESTIONS!!! I'LL GIVE 30 POINTS AND A BRAINIEST:)

Chemistry

2 answers:

Delvig [45]2 years ago

5 0

1 , mag shells a, d i hope this helped

mestny [16]2 years ago

3 0

Answer: 1, magnesium & mg

2, two energy shells

Explanation:

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Given these reactions, X ( s ) + 1 2 O 2 ( g ) ⟶ XO ( s ) Δ H = − 668.5 k J / m o l XCO 3 ( s ) ⟶ XO ( s ) + CO 2 ( g ) Δ H = +

qwelly [4]

Answer: The $\Delta H^o_{rxn}$ for the reaction is -1052.8 kJ.

Explanation:

Hess’s law of constant heat summation states that the amount of heat absorbed or evolved in a given chemical equation remains the same whether the process occurs in one step or several steps.

According to this law, the chemical equation is treated as ordinary algebraic expressions and can be added or subtracted to yield the required equation. This means that the enthalpy change of the overall reaction is equal to the sum of the enthalpy changes of the intermediate reactions.

The given chemical reaction follows:

$X(s)+\frac{1}{2}O_2(g)+CO_2(g)\rightarrow XCO_3(s)$ $\Delta H^o_{rxn}=?$

The intermediate balanced chemical reaction are:

(1) $X(s)+\frac{1}{2}O_2(g)\rightarrow XO(s)$ $\Delta H_1=-668.5kJ$

(2) $XCO_3(s)\rightarrow XO(s)+CO_2$ $\Delta H_2=+384.3kJ$

The expression for enthalpy of the reaction follows:

$\Delta H^o_{rxn}=[1\times \Delta H_1]+[1\times (-\Delta H_2)]$

Putting values in above equation, we get:

$\Delta H^o_{rxn}=[(1\times (-668.5))+(1\times (-384.3))=-1052.8kJ$

Hence, the $\Delta H^o_{rxn}$ for the reaction is -1052.8 kJ.

7 0

3 years ago

A medical research lab in Europe is studying a drug’s absorption in the blood. Another lab in Japan is trying to delay the elimi

ladessa [460]

The correct answer is From different social and ethnic backgrounds.

Explanation:

The purpose of science studies is to gain an understanding of specific phenomena and use this in the benefit of the world or humanity. Moreover, science is guided by objective methods and these are applied all around the world. This feature allows scientists from all kinds of social and ethnic backgrounds to study the same phenomena and obtain similar results, which is essential for the progress of scientific knowledge. This is exemplified by two different labs in two different countries studying drug absorption because the results of these two studies can be analyzed together to understand drug absorption.

In this context, one factor that contributes to the progress of scientific knowledge is the effort of scientists "from different social and ethnic backgrounds".

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3 years ago

When the moon moves directly between the sun and Earth and casts its shadow over part of Earth, you are

chubhunter [2.5K]

Answer:C

Explanation:you are seeing a lunar eclipse when the moon moves directly between the sun and the earth and casts a shadow. Hope this helps!

7 0

2 years ago

Read 2 more answers

How could Mendeleev predict the properties of elements that had not yet been discovered?

icang [17]

It was the element of aluminium where they predict their properties