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grigory [225]
3 years ago
11

The isotope Np-238 has a half life of 2.0 days if 96 grams of it were present on Monday how much will remain six days later

Chemistry
1 answer:
Kipish [7]3 years ago
3 0

Answer:

12.02 g

Explanation:

From the question given above, the following data were obtained:

Half life (t½) = 2 days

Original amount (N₀) = 96 g

Time (t) = 6 days

Amount remaining (N) =..?

Next, we shall determine the rate of disintegration of the isotope. This can be obtained as follow:

Half life (t½) = 2 days

Decay constant (K) =?

K = 0.693 / t½

K = 0.693 / 2

K = 0.3465 /day

Therefore, the rate of disintegration of the isotope is 0.3465 /day.

Finally, we shall determine the amount of the isotope remaining after 6 days as follow:

Original amount (N₀) = 96 g

Time (t) = 6 days

Decay constant (K) = 0.3465 /day.

Amount remaining (N) =.?

Log (N₀/N) = kt / 2.303

Log (96/N) = (0.3465 × 6) / 2.303

Log (96/N) = 2.079/2.303

Log (96/N) = 0.9027

Take the anti log of 0.9027

96/N = anti log (0.9027)

96/N = 7.99

Cross multiply

96 = N × 7.99

Divide both side by 7.99

N = 96 /7.99

N = 12.02 g

Therefore, the amount of the isotope remaining after 6 days is 12.02 g

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Vikentia [17]

C.)Cool air near the surface forms high-pressure areas; warm air forms low-pressure areas.

Explanation:

The relationship between air temperature and high and low pressure air is such that cool air near the surface forms high-pressure areas and warm air forms low pressure areas.

  • Cool air is closer to the surface because it has low kinetic energy to move. It is denser.
  • Warm air rises sharply away from the ground surface.
  • They form low pressure areas and their molecules are wide apart due to their high kinetic energy. The air is less dense.

learn more;

Kinetic energy brainly.com/question/9924094

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7 0
3 years ago
Which of the following is generally FALSE? Group of answer choices Elements in the same group have the same valence electron con
Whitepunk [10]

Answer: Option (c) is the correct answer.

Explanation:

Generally, when we move from top to bottom in a group then there occur increase in the number of electrons due to which there will also occur increase in the number of shells.

As atomic size is the distance between the nucleus and valence shell of an atom. Hence, more is the number of shells present in an atom more will be its atomic radius.

Thus, we can conclude that the statement atomic radius of elements in a group decreases as you go from top to bottom, is generally FALSE.

3 0
3 years ago
Rank the following molecules (1st, 2nd, 3rd, 4th) in the order that they melt.
Daniel [21]

Sodium chloride has the highest melting point while iodine has the least melting point.

The melting points of solid substances depends on the nature of intermolecular forces that exists in the substance. The stronger the magnitude of intermolecular forces in a substance, the higher its melting point.

The order of melting points of the solids shown in question is as follows;

  • 1st - Sodium chloride
  • 2nd - sucrose
  • 3rd - paraffin
  • 4th - Iodine

Sodium chloride has the highest melting points because it is an ionic substance. Among the molecular sucrose and paraffin, sucrose has a higher melting point than sucrose because it has a greater molar mass. Iodine, a molecular substance has the least molar mass and the least melting point in the list.

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6 0
2 years ago
If you react 156.0 g of calcium chloride with an excess NaOH, how much sodium chloride should you get?
laiz [17]

Answer:

164.3g of NaCl

Explanation:

Based on the chemical equation:

CaCl2 + 2NaOH → 2NaCl + Ca(OH)2

<em>where 1 mole of CaCl2 reacts with 2 moles of NaOH</em>

To solve this question we must convert the mass of CaCl2 to moles. Using the chemical equation we can find the moles of NaCl and its mass:

<em>Moles CaCl2 -Molar mass: 110.98g/mol-</em>

156.0g CaCl₂ * (1mol / 110.98g) = 1.4057 moles CaCl2

<em>Moles NaCl:</em>

1.4057 moles CaCl2 * (2mol NaCl / 1mol CaCl2) = 2.811 moles NaCl

<em>Mass NaCl -Molar mass: 58.44g/mol-</em>

2.811 moles NaCl * (58.44g / mol) = 164.3g of NaCl

7 0
2 years ago
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Serjik [45]

Answer:

The metals are on the bottom left in the periodic table, and the nonmetals are at the top right. The semimetals lie along a diagonal line separating the metals and nonmetals. The elements are arranged in a periodic table, which is probably the single most important learning aid in chemistry.

Explanation:

im not sure if there was supposed to options to that question or not

7 0
3 years ago
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