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Natali5045456 [20]

3 years ago

15

How long will it take for a 40.0 gram sample of I-131 (half-life = 8.040 days) to decay to 1/100 its original mass? ( PLEASE WIT

H DETAILS)

1 answer:

masya89 [10]3 years ago

4 0

Idk how long will it

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Someone please help! Hurry

makkiz [27]

It’s b) Phototropism

4 0

3 years ago

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Suppose a 10.0 mL sample of an unknown

mote1985 [20]

The concentration of HCl is equal to 2.54mol/L.

<h3>Mole calculation</h3>

To solve this question, one must use the molarity calculation, which corresponds to the following expression:

$M = \frac{mol}{v}$

Thus, to find the molarity of the sample, the following calculations must be performed:

$V_f = 10ml + 625ml = > 635ml$

$\frac{0.004mol}{xmol} =\frac{1000ml}{635ml}$

$x = 0.00254 mol$

So, 0.00254 moles were added per 10ml, so we can do:

$\frac{0.00254mol}{xmol}= \frac{10ml}{1000ml} \\x = 2.54mol/L$

So, the concentration of HCl is equal to 2.54mol/L.

Learn more about mole calculation in: brainly.com/question/2845237

6 0

2 years ago

In your own words, describe two conditions that are necessary for an eclipse to occur

Rzqust [24]

1. the Moon must be in line with the Earth and Sun - New Moon for a solar eclipse and Full Moon for a lunar eclipse.2. the Moon must be at one of its nodes. Most of the time the Moon at New or Full passes above or below the Sun because its orbit is tilted relative to the ecliptic. An eclipse can occur only when it is at a node, in other words crossing the ecliptic.

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3 years ago

What is the difference between metallic and non metallic oxides?

Sveta_85 [38]

Answer:

Metal oxides are compounds composed of metal ions and oxide ions. Nonmetal oxides are compounds composed of nonmetal atoms and oxygen atoms. The main difference between metal oxides and non metal oxides is that metal oxides are basic compounds whereas nonmetal oxides are acidic compounds.

Explanation:

have a great day ahead

tC

4 0

2 years ago

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Group the following electron configurations in pairs that would represent similar chemical properties at their atoms;

marishachu [46]

<u>Answer:</u> Pairs are: (a) and (d), (b) and (f), (c) and (e)

<u>Explanation:</u>

In a periodic table, elements are arranged in 18 vertical columns known as groups and 7 horizontal rows known as periods.

Elements arranged in a group show similar chemical properties because of the presence of same number of valence electrons.

Valence electrons are defined as the electrons which are present in the outermost shell of an atom. Outermost shell has the highest value of 'n' that is principal quantum number.

For the given options:

<u>For a:</u>

The given electronic configuration is: $1s^22s^22p^63s^2$

The number of valence electrons in the given configuration are 2

<u>For b:</u>

The given electronic configuration is: $1s^22s^22p^63s^3$

The number of valence electrons in the given configuration are [2 + 3] = 5

<u>For c:</u>

The given electronic configuration is: $1s^22s^22p^63s^23p^64s^23d^{10}4p^6$

The number of valence electrons in the given configuration are [2 + 6] = 8

<u>For d:</u>

The given electronic configuration is: $1s^22s^2$

The number of valence electrons in the given configuration are 2

<u>For e:</u>

The given electronic configuration is: $1s^22s^22p^6$

The number of valence electrons in the given configuration are [2 + 6] = 8

<u>For f:</u>

The given electronic configuration is: $1s^22s^22p^63s^23p^3$

The number of valence electrons in the given configuration are [2 + 3] = 5

Electronic configuration of (a) and (d) will form a pair, (b) and (f) will form a pair, (c) and (e) will form a pair and will have similar chemical properties.

Hence, the pairs are: (a) and (d), (b) and (f), (c) and (e)

4 0

3 years ago