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3 years ago

¡¡¡PLEASE HELP!!! I'm stuck on a question..

Chemistry

1 answer:

Reptile [31]3 years ago

7 0

The half life of uranium- 238 is

4.46 x10^9 years

Explanation

Half life is the time taken for the radioactivity of a isotope to fall to half its original value.

The original mass of uranium-238 is 4.0 mg

Half of original mass of uranium = 4.0 mg /2 = 2.0 mg

since it take 4.46 x 10^ 9 years for the sample to half the half life of uranium -238 = 4.46 x10^9 years

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Makovka662 [10]

Answer:

Explanation:

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3 years ago

Without consulting Figure 28 or Table 22, determine whether each of the following electron configurations is an inert gas,a halo

Anna [14]

This is an incomplete question, here is a complete question.

Determine whether each of the following electron configurations is an inert gas, a halogen, an alkali metal, an alkaline earth metal, or a transition metal. Justify your choices.

(a) $1s^22s^22p^63s^23p^5$

(b) $1s^22s^22p^63s^23p^63d^74s^2$

(d) $1s^22s^22p^63s^23p^64s^1$

(e) $1s^22s^22p^63s^23p^63d^24s^2$

(f) $1s^22s^22p^63s^2$

Answer :

(a) $1s^22s^22p^63s^23p^5$ → Halogen

(b) $1s^22s^22p^63s^23p^63d^74s^2$ → Transition metal

(c) $1s^22s^22p^63s^23p^63d^{10}4s^24p^6$ → Transition metal

(d) $1s^22s^22p^63s^23p^64s^1$ → Halogen metal

(e) $1s^22s^22p^63s^23p^63d^24s^2$ → Transition metal

(f) $1s^22s^22p^63s^2$ → Alkaline earth metal

Explanation :

Inert gas : These are the gases which lie in group 18.

Their general electronic configuration is: $ns^2np^6$ where n is the outermost shell.

Halogen : These are the elements which lie in group 17.

Their general electronic configuration is: $ns^2np^5$ where n is the outermost shell.

An alkali metal : These are the elements which lie in group 1.

Their general electronic configuration is: $ns^1$ where n is the outermost shell.

An alkaline earth metal : These are the elements which lie in group 2.

Their general electronic configuration is: $ns^2$ where n is the outermost shell.

Transition elements : They are the elements which lie between 's' and 'p' block elements. These are the elements which lie in group 3 to 12. The valence electrons of these elements enter d-orbital.

Their general electronic configuration is: where n is the outermost shell.

(a) $1s^22s^22p^63s^23p^5$

The element having this electronic configuration belongs to the halogen family.

(b) $1s^22s^22p^63s^23p^63d^74s^2$

The element having this electronic configuration belongs to the transition family.

(c) $1s^22s^22p^63s^23p^63d^{10}4s^24p^6$

The element having this electronic configuration belongs to the transition family.

(d) $1s^22s^22p^63s^23p^64s^1$

The element having this electronic configuration belongs to the halogen family.

(e) $1s^22s^22p^63s^23p^63d^24s^2$

The element having this electronic configuration belongs to the transition family.

(f) $1s^22s^22p^63s^2$

The element having this electronic configuration belongs to the an alkaline earth metal.

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3 years ago

A chemistry student answered 81 questions correctly on a 90-question test. What

nika2105 [10]

Answer:

90%

Explanation:

it will be 81/90 ×100/1

81 over 90 × 100 over 1

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3 years ago

Water difference between glacier and geyser

Gekata [30.6K]

Glaciers are found in areas where the net accumulation of snow exceeds the melt, therefore they are usually found in areas of high elevation, cold temperatures, and high precipitation.

Geysers are found in areas of shallow crust with high heat flow, such as hot spots.

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3 years ago

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Steam is sometimes used to melt ice. Is this change physical or chemical?

Anon25 [30]

Steam is the gaseous phase of water. It is used in some cases to melt ice. Melting of ice is the conversion of solid water to liquid water. This is just a phase change in which water changes its state from solid state to liquid state. But the chemical composition of water $H_{2}O$ remains unchanged. Water has the same molecular formula in both the solid (ice) and liquid states. Hence, the conversion of solid ice to liquid water by steam refers to a physical change.

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3 years ago