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vagabundo [1.1K]
3 years ago
7

How much of a sample remains after five half-lives have occurred?

Chemistry
1 answer:
hammer [34]3 years ago
5 0
The answer is 1/32

The first half-life, we have 1 • 1/2 = 1/2 left.
After two: 1/2 • 1/2 = 1/4
Three: 1/4 • 1/2 = 1/8
Four: 1/8 • 1/2 = 1/16
And five: 1/16 • 1/2 = 1/32.
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_____ might be able to detect tumors based on its use of X-rays and ability to produce cross-sectional images of the brain.
MatroZZZ [7]

Answer: CAT (computerized axial tomography) scan

Explanation:

Computerized Axial Tomography (CAT) scan is an X-ray examination in which a computer generates images showing cross-section views of a patient's internal parts (brain, blood vessels and etc.)

CAT scan can identify normality and detect abnormalities (such as tumor and degenerated cells) in the internal organs and structures and hence, this information are used to guide other medical processes.

6 0
3 years ago
90 POINTSSSS!!!
Katarina [22]

Answer:

\large \boxed{\text{-2043.96 kJ/mol}}

Explanation:

Assume the reaction is the combustion of propane.

Word equation: propane plus oxygen produces carbon dioxide and water

Chemical eqn:    C₃H₈(g) +   O₂(g) ⟶   CO₂(g) +   H₂O(g)

Balanced eqn:    C₃H₈(g) + 5O₂(g) ⟶ 3CO₂(g) + 4H₂O(g)

(a) Table of enthalpies of formation of reactants and products

\begin{array}{cc}\textbf{Substance} & \textbf{$\Delta_{\text{f}}$H/(kJ/mol}) \\\text{C$_{3}$H$_{8}$(g)} & -103.85 \\\text{O}_{2}\text{(g)} & 0 \\\text{CO}_{2}\text{(g)} & -393.51 \\\text{H$_{2}$O(g)} & -241.82\\\end{array}

(b)Total enthalpies of reactants and products

\Delta_{\text{rxn}}H^{\circ} = \sum \left( \Delta_{\text{f}} H^{\circ} \text{products}\right) - \sum \left (\Delta_{\text{f}}H^{\circ} \text{reactants} \right)\\= \text{-2147.81 kJ/mol - (-103.85 kJ/mol)}\\=  \text{-2147.81 kJ/mol + 103.85 kJ/mol}\\= \textbf{-2043.96 kJ/mol}\\\text{The enthalpy change is $\large \boxed{\textbf{-2043.96 kJ/mol}}$}

ΔᵣH° is negative, so the reaction is exothermic.

5 0
3 years ago
6. Which of the following could be a base in a water solution?
Elza [17]

Answer:

h20

Explanation:

H2O is an acid and a base, and H20 is water.

5 0
3 years ago
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ycow [4]
Carbs!! (or carbohydrates)
7 0
3 years ago
Read 2 more answers
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MrRissso [65]

Answer: Vibråtory movement.

Explanation: when particles bounce against each other the friction creates thermal energy. Think about what happens when you rub your hands together and they get warmer, that the friction between your hands making thermal energy.

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