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2 years ago

The half-life of 131I is 80 days. How much of a 500.0 mg sample remains after 3 half lives?

Chemistry

1 answer:

I am Lyosha [343]2 years ago

6 0

Answer:

62.5 mg

Explanation:

Just multiply the original amount by 1/2 three times:

500 mg x 1/2 x 1/2 x 1/2 = 62.5 mg

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WILL GIVE BRAINLIEST Explain why HS2 has a bent geometry, while BeH2 has a linear geometry.

Natali5045456 [20]

Answer:

H2S has a bent geometry, while BeH2 has a linear geometry because: presence of lone pair in H2S

Absence of Lone pair in BeH2

Explanation:

Structure of H2S :

Atomic number of S = 16 = 1s(2 )2s(2) 2p(6) 3s(2 )3p(4)

Outer most shell has 6 electron

Valence electron (Involved in bonding) = 6

Out of these 6 electrons ,

2 electrons are formed in bonding with Hydrogen

Rest 4 are non- bonding and present as lone - pair

H2S exist - sp3 hybridisation

There are 2-Lone pair on S in H2S (look at the image attached)

Structure of H2S :

Atomic number of Be = 4 = 1s(2 ) 2s(2)

Valence electron (Involved in bonding) = 2

These 2- electron are involved in bonding with two Hydrogen and form liner shape.*Form sp - hybridized

Hence shape is linear because it has non - lone pair.

VSEPR : According to this theory lone pair causes repulsion to the bond and cause unstability in the molecule.

Hence the bonds shifts away from lone pairs . This is why H-S bonds in H2S shifts way from lone pair

5 0

3 years ago

Why have we not drilled or mined deeper into earth ??

alexdok [17]

Scientists have determined that the center of the earth is 6371 km below the surface. But how has this been determined? Many people might answer that question by saying scientists can drill into the Earth with machines. However, the drilling rigs that scientists use can only drill about 20 km in the Earth which is not very deep! In other words, we can only drill into upper part of the crust of the earth. Extremely high temperatures and pressures within the Earth make drilling into it very difficult

8 0

3 years ago

To make a 6.50M solution, how many moles of solute will be needed if 12.0 liters of solution are required

avanturin [10]

Answer:

78 moles of the solute

Explanation:

From the question;

Molarity of the solution is 6.50 M
Volume of the solution is 12.0 L

We want to determine the number of moles needed

We need to know that;

Molarity = Number of moles ÷ Volume

Therefore;

Number of moles = Molarity × Volume

Hence;

Number of moles = 6.50 M × 12.0 L

= 78 moles

Thus, the moles of the solute needed is 78 moles

8 0

3 years ago

A weather balloon has a volume of 105L at 0.97 atm when the temperature is 318K. What is the volume

chubhunter [2.5K]

Answer:

89 L

Explanation:

Step 1: Given data

Initial pressure (P₁): 0.97 atm

Initial volume (V₁): 105 L

Initial temperature (T₁): 318 K

Final pressure (P₂): 1.05 atm

Final volume (V₂): ?

Final temperature (T₂): 293 K

Step 2: Calculate the final volume of the weather balloon

If we assume that the gas inside the balloon behaves as an ideal gas, we can calculate the final volume of the gas using the combined gas law.

P₁ × V₁ / T₁ = P₂ × V₂ / T₂

V₂ = P₁ × V₁ × T₂ / T₁ × P₂

V₂ = 0.97 atm × 105 L × 293 K / 318 K × 1.05 atm = 89 L

3 0

3 years ago

Who is Gilbert Newton lewis

skelet666 [1.2K]

Gilbert N. Lewis (1875-1946) was an American physical chemist.

His work with heavy water and resources were adapted by Ernest Lawrence in the development of the cyclotron.

SCIENTIFIC CONTRIBUTIONS

Lewis made many contributions to science. He was nominated for the Nobel Prize 41 times, though he was never awarded the prize.

He discovered covalent bonds and electron pairs. He worked with isotope separation, and became the first person to purify a sample of heavy water. The heavy water was later used as projectiles in Lawrence’s 27-inch cyclotron.

He also made contributions in ideas on relativity and acid-base reactions and coined the term “photon” as the smallest unit of light.

8 0

3 years ago