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Vladimir79 [104]
4 years ago
12

A sample contains 2.2 g of the radioisotope niobium-91 and 15.4 g of its daughter isotope, zirconium-91.

Chemistry
2 answers:
Fudgin [204]4 years ago
8 0

Time to decay : 2040 years

Further explanation  

The atomic nucleus can experience decay into 2 particles or more due to the instability of its atomic nucleus.  

Usually radioactive elements have an unstable atomic nucleus.  

The main particles are emitted by radioactive elements ,so that they generally decay, are alpha (α), beta (β) and gamma (γ) particles  

General formulas used in decay:  

\tt Nt=No.\dfrac{1}{2}^{\dfrac{T}{t\frac{1}{2} }  

T = duration of decay  

t 1/2 = half-life  

N₀ = the number of initial radioactive atoms  

Nt = the number of radioactive atoms left after decaying during T time  

moles zirconium :

\tt \dfrac{15.4}{91}=0.169

moles niobium :

\tt \dfrac{2.2}{91}=0.0242

the half-life of niobium-91 is 680 years

Reaction

⁹¹₄₁Nb ⇒⁹¹₄₀Zr + ₁⁰e

Amount of Nb from reaction : 0.169

Amount of initial Nb = 0.0242 + 0.169 = 0.1932

Time to decay (T) :

\tt 0.0242=0.1932.\dfrac{1}{2}^{\dfrac{T}{680}}\\\\0.1252=\dfrac{1}{2}^{\dfrac{T}{680}}\\\\\dfrac{1}{2}^{3}=\dfrac{1}{2}^{\dfrac{T}{680}}\\\\T=680\times 3=2040

noname [10]4 years ago
5 0

Answer:

It’s CCCCCCCCCCCCCCC

Explanation:

I just took the instruction and yes its “C.”

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Answer:

Correct answer is (D). as a weak acid it can cross the membrane when in its uncharged form.

Explanation:

Aspirin (acetylsalicylic acid, ASA) is an analgesic and anti-inflammatory agent use in the treatment of gentle to moderate pain, inflammation and fever. It is absorb in the stomach and intestine in an unchanged form.

6 0
4 years ago
Which is the solubility product expression for pbcl2(s)
Sever21 [200]
The answer is [Pb^2+][Cl-]^2
4 0
3 years ago
A 0.89% (w/v) sodium chloride solution is referred to as physiological saline solution because it has the sameconcentration of s
elixir [45]

Answer: Molarity of a physiological saline solution is 0.15 M

Explanation:

Molarity of a solution is defined as the number of moles of solute dissolved per liter of the solution.

Molarity=\frac{n\times 1000}{V_s}

n = moles of solute

V_s =volume of solution in ml

Given : 0.89 g of sodium chloride in 100 ml of solution.

To calculate the moles, we use the equation:

\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}=\frac{0.89g}{58.5g/mol}=0.015moles

Volume of solution = 100 ml

Molarity=\frac{0.015\times 1000}{100ml}=0.15M

Molarity of physiological saline solution is 0.15 M

4 0
3 years ago
Indicate the oxidation number of oxygen for each compound in the following reaction: 2H2O2(aq)→ 2H2O(l) O2(g) Select the choice
Aleksandr [31]

Answer:

2H2O2(aq)→ 2H2O(l) O2(g) : The oxidation number of oxygen for each compound is -1, -2, 0

Explanation:

In peroxides the oxidation state of oxygen is -1, since one oxygen bonds to the other oxygen and a hydrogen and the bound oxygen captures the electron of the remaining hydrogen. Through a scheme would be

H --- O --- O --- H

We remember that oxygen needs two electrons to get to have the configuration of the nearest noble gas (Lewis octet rule). In Peroxides, the oxygen is linked by covalent bonds. If we take it strictly, peroxide is a grouping of two oxygen, having the whole valence -2. which is why it is usually said that it is when oxygen has a valence -1

As we said the oxidation state is -2, the one that appears in the water molecule, since Hydrogen acts with valence +1 and it is 2 atoms that give up electrons to compensate for oxygen.

In the O2 it acts with valence 0 since we talk about gas in its elementary state. All diatomic molecules in their elemental state, generally gases or metals in solid state, act with a valence of 0.

3 0
3 years ago
Equation is balanced already
mojhsa [17]

Answer:

1.) 13 g C₄H₁₀

2.) 41 g CO₂

Explanation:

To find the mass of propane (C₄H₁₀) and carbon dioxide (CO₂), you need to (1) convert mass O₂ to moles O₂ (via molar mass), then (2) convert moles O₂ to moles C₄H₁₀/CO₂ (via mole-to-mole ratio from equation coefficients), and then (3) convert moles C₄H₁₀/CO₂ to mass C₄H₁₀/CO₂ (via molar mass). It is important to arrange the ratios in a way that allows for the cancellation of units. The final answers should have 2 sig figs to match the sig figs of the given value.

Molar Mass (C₄H₁₀): 4(12.011 g/mol) + 10(1.008 g/mol)

Molar Mass (C₄H₁₀): 58.124 g/mol

Molar Mass (CO₂): 12.011 g/mol + 2(15.998 g/mol)

Molar Mass (CO₂): 44.007 g/mol

Molar Mass (O₂): 2(15.998 g/mol)

Molar Mass (O₂): 31.996 g/mol

2 C₄H₁₀ + 13 O₂ ----> 8 CO₂ + 10 H₂O

 48 g O₂             1 mole             2 moles C₄H₁₀            58.124 g
---------------  x  -----------------  x  -------------------------- x  ------------------  =  
                         31.996 g              13 moles O₂               1 mole

=  13 g C₄H₁₀

 48 g O₂             1 mole               8 moles CO₂            44.007 g
---------------  x  -----------------  x  -------------------------- x  ------------------  =  
                         31.996 g              13 moles O₂               1 mole

=  41 g CO₂

6 0
2 years ago
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