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2 years ago

Scientists Discuss time and how old the Earth is. How do they measure the idea

1 answer:

4 0

The following is the introduction to a special e-publication called Determining the Age of the Earth (click the link to see a table of contents). Published earlier this year, the collection draws articles from the archives of Scientific American. In the collection, this introduction appears with the title, “Stumbling Toward an Understanding of Geologic Timescales.”

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The mass of an atom comes from _____. A. the nucleus B. the neutrons C. the electrons D. the protons

kramer

Answer:

The answer is C

Explanation:

4 0

2 years ago

Which of the following best describes the difference in bonding between two hydrogen atoms and two carbon atoms?

valentinak56 [21]

Answer :

2. Hydrogen forms bonds through the overlap of 1s atomic orbitals and the sharing of electrons between atoms. Carbon forms bonds through the overlapping of sp hybrid atomic orbitals and the sharing of electrons between carbon atoms.

Explanation:

The H-H bond is formed by the overlap of two 1s orbitals and the sharing of electrons between the two atoms.

A carbon atom must use the overlap of hybridized atomic orbitals and the sharing of electrons to bond with another carbon atoms.

1. is wrong because H can use only its 1s orbital for bonding.

3. is wrong because C must share electrons to form a carbon-carbon bond.

4. is wrong because C does NOT use overlapping of 2s orbitals for bonding. It uses the overlap of hybridized orbitals.

5. is wrong because H must share electrons to form an H-H bond.

4 0

2 years ago

Help me please I need to pass my exam

Troyanec [42]

Answer:

I think it is 1115 kJ but I don't see the answer

Explanation:

8 0

2 years ago

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kirill [66]

Well,

I guess the answer would be....

.

6 0

2 years ago

Read 2 more answers

The rate constant k for a certain reaction is measured at two different temperatures:

bogdanovich [222]

Answer:

Ea=5.5 Kcal/mole

Explanation:

Let rate constant are $K_1$ and $K_2$ at temperature $T_1$ and $T_2$

By using Arrhenius equation at two different two different temperature,

$Log K_1/K_2 =E_a/2.303R*(1/T_2 -1/T_2 );T_1=273+376=649K ;K_1=4.8*10^8;T_2=273+280=553K ;K_2=2.3*10^8;R=2 cal/(mole.K);Log (4.8*10^8)/(2.3*10^8 )=E_a/2.303R*(1/553K-1/649); Log 4.8/2.3=E_a/2.303R*96/358897 ;0.32=E_a/2.303R*96/358897;E_a=(0.32*2.303R*358897)/96;$

By putting value of R=2 cal/mole.K

$E_a=5510.265cal/mole;$

By rounding off upto 2 significant figure;

$E_a=5.5Kcal/mole;$

8 0

2 years ago