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3 years ago

The pollen grains move in water randomly because of

Chemistry

1 answer:

polet [3.4K]3 years ago

6 0

A the collisions between water particles and polllen grains

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What is a beta particle ?

shtirl [24]

A Beta Particle is <span>a fast-moving electron emitted by radioactive decay of substances.</span>

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4 years ago

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Calculate the number of oxygen atoms in a 80.0 g sample of scheelite (CaWo).

castortr0y [4]

Answer:

Explanation:

scheelite is CaWO₄

Mol weight = 288

80 g of scheelite = 80 / 288 = 27.77 x 10⁻² moles

27.77 x 10⁻² moles of scheelite = 27.77 x 10⁻² x 6.02 x 10²³ molecules of scheelite

= 167.17 x 10²¹ molecules of scheelite

1 molecule of scheelite contains 4 atoms of oxygen

167.77 x 10²¹ molecules of scheelite contains 4 x 167.77 x 10²¹ atoms of oxygen .

= 671.08 x 10²¹ atoms of oxygen .

= 671 x 10²¹ atoms .

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3 years ago

Need help fast please 20 points

artcher [175]

Answer:

gamma radiation

Explanation:

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3 years ago

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Analysis of a rock sample shows that it contains 6.25% of its original uranium-235. How old is the rock? How do you know?

nadya68 [22]

Answer:

$2.82\cdot 10^9 y$

Explanation:

A radioactive isotope is an isotope that undergoes nuclear decay, breaking apart into a smaller nucleus and emitting radiation during the process.

The half-life of an isotope is the amount of time it takes for a certain quantity of a radioactive isotope to halve.

For a radioactive isotope, the amount of substance left after a certain time t is:

$m(t)=m_0 (\frac{1}{2})^{\frac{t}{\tau}}$ (1)

where

$m_0$ is the mass of the substance at time t = 0

m(t) is the mass of the substance at time t

$\tau$ is the half-life of the isotope

In this problem, the isotope is uranium-235, which has a half-life of

$\tau=7.04\cdot 10^8 y$

We also know that the amount of uranium left in the rock sample is 6.25% of its original value, this means that

$\frac{m(t)}{m_0}=\frac{6.25}{100}$

Substituting into (1) and solving for t, we can find how much time has passed:

$t=-\tau log_2 (\frac{m(t)}{m_0})=-(7.04\cdot 10^8) log_2 (\frac{6.25}{100})=2.82\cdot 10^9 y$

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4 years ago

Are all metals solid?

xxTIMURxx [149]

Answer: No

Explanation:

Example , Mercury is a Liquid metal

4 0

4 years ago