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3 years ago

Choose the FALSE statement.

Chemistry

1 answer:

Mariana [72]3 years ago

5 0

Answer:

C. The half-life of C-14 is about 40,000 years.

Explanation:

The only false statement from the options is that the half-life of C-14 is 40,000yrs.

The half-life of an isotope is the time it takes for half of a radioactive material to decay to half of its original amount. C-14 has an half-life of 5730yrs. This implies that during every 5730yrs, C-14 will reduce to half of its initial amount.

All living organisms contain both stable C-12 and the unstable isotope of C-14
The lower the C-14 compared to the C-12 ratio in an organism, the older it is.

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Which plant characteristic is the least important with regard to attracting bats? (1 point)

Sav [38]

Answer:

O flower shape

Explanation:

Bats are just as important for pollination as insects and just like insects, plants use artifices to attract bats to their flowers, allowing them to have access to the pollen that will be taken elsewhere.

Bats are mainly attracted by the color and smell of flowers, the size and shape also play a role in attracting these animals, but the shape is less influential.

7 0

3 years ago

To sum up the question: why are some parts of the body more sensitive than others?

natulia [17]

Answer:

Some areas of the body are more sensitive than others because they have more nerve endings. It hurts when you bite your tongue because the sides of your tongue have a lot of nerve endings that are very sensitive to pain! The tongue, lips, and fingertips are the most touch-sensitive parts of the body. The parts of your skin that need to be most sensitive like your fingertips and your lips have more receptor cells in them than others less sensitive areas. The least sensitive skin on the human body is found in the heel area. This is because there are very few nerves in the heel to feel things. If there were too many nerves in our heels then walking would be far too painful.

Explanation:

5 0

3 years ago

Read 2 more answers

Write E in the blank if the material is heterogeneous or O if it is homogeneous.

Advocard [28]

Answer/Explanation:

Wood: E

Freshly brewed black coffee: O

Water: O

Lucky Charms: E

Salt: O

Dirt: E

Sausage and mushroom pizza: E

Air: O

Milk: O

Gold: O

Any mixture that looks the same through the substance is homogenous. The different parts are unable to be visibly seen. (Any periodic element is homogenous)

Any mixture that can be easily determined a mix and cannot be evenly separated or dispersed is heterogenous.

8 0

3 years ago

Convert the composition of the following alloy from atom percent to weight percent (a) 44.9 at% of silver, (b) 46.3 at% of gold,

vesna_86 [32]

Answer:

Mass percentage of gold : 33.35%

Mass percentage of silver: 62.80%

Mass percentage of copper : 3.85%

Explanation:

$N=n\times N_A$

Where : N = Number of atoms

n = moles

$N_A=6.022\times 10^{23}$ = Avogadro number

Let the total atoms present in the alloy be 100.

Atom percentage of silver = 44.9%

Atoms of of silver = 44.9% of 100 atoms = 44.9

Atomic weight of silver = 107.87 g/mol

Mass of 44.9 silver atoms = 107.87 g/mol × 44.9 = 4,843.363 g/mol

Atom percentage of gold= 46.3%

Atoms of of gold = 46.3% of 100 atoms = 46.3

Atomic weight of gold = 196.97 g/mol

Mass of 44.9 gold atoms = 196.97 g/mol × 46.3 = 9,119.711 g/mol

Atom percentage of copper = 8.8 %

Atoms of of copper = 8.8% of 100 atoms = 8.8

Atomic weight of copper = 63.55 g/mol

Mass of 44.9 copper atoms = 63.55 g/mol × 8.8 = 559.24 g/mol

Total mass of an alloy :4,843.363 g/mol + 9,119.711 g/mol + 559.24 g/mol

Mass percentage of gold :

$\frac{4,843.363 g/mol}{4,843.363 g/mol + 9,119.711 g/mol + 559.24 g/mol}\times 100=33.35 \%$

Mass percentage of silver:

$\frac{9,119.711 g/mol}{4,843.363 g/mol + 9,119.711 g/mol + 559.24 g/mol}\times 100=62.80\%$

Mass percentage of copper :

$\frac{559.24 g/mol}{4,843.363 g/mol + 9,119.711 g/mol + 559.24 g/mol}\times 100=3.85\%$

7 0

3 years ago

Express the pressure 545 mm Hg in kilopascals.

Arlecino [84]

545mm Hg in Kilopascals is 72.6607

I hope this helps you. Good luck stay safe, healthy and, happy!<3

6 0

3 years ago