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Akimi4 [234]
3 years ago
11

A radioactive nucleus alpha decays to yield a sodium-24 nucleus in 14.8 hours. What was the identity of the original nucleus?

Chemistry
1 answer:
Rudik [331]3 years ago
5 0
Answer:

<span>2813Al</span>

Explanation:

You know that alpha decay takes place when a α-particle is being ejected from the nucleus of a radioactive isotope.An 

<span>α-particle</span> is simply the nucleus of a helium-4 atom. A helium-4 atom has a total of two protons and two neutrons in its nucleus, and two electrons surrounding that nucleus.

In that case, if a <span>α-particle</span> is the nucleus of a helium-4 atom, then it must have a mass number equal to 4, since it has two protons and two neutrons, and a net charge of <span>(2+)</span> since it no longer has the two electrons that the helium-4 atom has.

So, you know that an unknown radioactive isotope decays via alpha decay to yield a sodium-24 nucleus.

A sodium-24 nucleus contains 11 protons and 13 neutrons. This means that you can write

<span><span>AZ</span>X→<span>2411</span>Na+<span>42</span>α</span>

Here A and Z represent the unknown element's mass number and atomic number, respectively.

So, if you take into account the fact that mass number and atomic number must be conserved in a nuclear reaction, you can say that

<span>A=24+4 </span> and <span> Z=11+2</span>

The unknown isotope will thus have

<span>{<span><span>A=28</span><span>Z=13</span></span></span>

A quick look at the periodic table will show you that the element that has 13 protons in its nucleus is aluminum, Al. This means that you're dealing with aluminum-28, an isotope of aluminum that has 15 neutrons in its nucleus.

The complete nuclear equation will be

<span><span>2813</span>Al→<span>2411</span>Na+<span>42</span><span>α
</span></span>

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s sample of thorium-234 has a half life of 25 days. will all the thorium undergo radioactive decay in 50 days?
Assoli18 [71]

Answer:

25% thorium will left after 50 days.

Explanation:

Half life:

A nuclear half is the time period of radioactive material in which its amount remain halved.

In given question it is stated that the half life thorium-234 is 25 days. Which means after passing the 25 days the amount of thorium must be halved of original amount.

For example,

If the original concentration was 100%, than after 25 days it will be 50%.

After 50 days amount of thorium left:

Number of half life = T (elapsed) / T half life

Number of half life = 50/25

Number of half life =  2

At first half life amount of thorium left = 100/2 = 50

After second half life amount of thorium left = 50/2 = 25

Total amount decayed = 50+25 = 75

Amount left after 50 days = 100-75 = 25

25% thorium will left after 50 days.

5 0
3 years ago
Three different samples were weighed using a different type of balance for each sample. The three were found to have masses of 0
Lena [83]

Answer:

6.096799125kg

Explanation:

According to the question, three different samples weighed using different types of balance had masses: 0.6160959 kg, 3.225 mg, and 5480.7 g.

Based on observation, the mass units in the three measurements are different but must be uniform in order to find the total mass. Hence, we need to convert to the standard unit (S.I unit of mass), which is kilograms (kg)

Since 1kg equals 1,000,000mg

Hence, 3.225mg will be 3.225/1000000

= 0.000003225kg

Also, 1kg equals 1000g

Hence, 5480.7g will be 5480.7/1000

= 5.4087kg

Hence, the total mass of the three samples (now in the same unit) are:

5.4807kg + 0.000003225kg + 0.6160959 kg

= 6.096799125kg

3 0
3 years ago
How many different atoms are there in H2SO4?
Alenkinab [10]
7, i'm pretty sure, hope I helped!
8 0
3 years ago
Classify methanal according to the position of the c=o group
seraphim [82]

Answer :  Methanal also known as Formaldehyde CH_{2}O is a chemical Aldehyde which contain ( -CHO) group.

Explanation :

In organic chemistry, a carbonyl group is a functional group which contain a carbon atom double-bonded to an oxygen atom i.e, ( C=O).

     If carbonyl group is present in a compound then it can be a carboxylic (RCOOH), aldehyde (RCHO), ketone (RCOR'), ester ((RCOOR') or amide (RCONR'R") group.

Here are some functional groups naming according to the<em> IUPAC</em> rules and image also attached,

Carboxylic acid   →    (RCOOH)    →    ( name end in 'OIC ACID' )

Aldehyde             →    (RCOH)       →    ( name end in 'AL' )

Ketone                 →    (RCOR')       →    ( name end in 'ONE' )

Ester                     →    (RCOOR')    →    ( name end in 'ATE' )

Amide                   →    (RCONR'R") →    ( name end in 'AMIDE' )

In an aldehyde, atleast one hydrogen atom must be attached to the carbonyl carbon. For an aldehyde, remove ( -e) from alkane name and add ( -al) at the end of the compound.

Methanal is the IUPAC name for Formaldehyde.


3 0
3 years ago
Which metal is more active than H2?<br> (1) Ag (3) Cu<br> (2) Au (4) Pb
astraxan [27]

Answer is (4) - Pb.


According to the reactivity series of elements

- the elements which are above the hydrogen are more reactive than hydrogen.

- the elements which are below the hydrogen are less reactive than hydrogen.


Among the given choices, only Pb is placed above the hydrogen in the reactivity series and rest are below the hydrogen.


Hence, Pb is more active than hydrogen.

5 0
3 years ago
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