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2 years ago

14

. Nhiệt độ ban đầu của 344 g một mẫu sắt là 18,2oC. Nếu mẫu sắt này hấp thụ 2,25 kJ nhiệt lượng thì nhiệt độ cuối của mẫu sắt nà

y là bao nhiêu? (CFe = 0,449 J/g.K).

2 answers:

Mrrafil [7]2 years ago

8 0

Answer:

ano poh paki ult kasi hindi mahintindihan yan question mo hindi mahintindihwn

padilas [110]2 years ago

4 0

Answer:

i can't understand the question

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The table below shows the density of a sample of a mystery liquid you tested in the lab. Can you infer the identity of the subst

Mashutka [201]

Answer:

A. Yes, the substance must be water.

Explanation:

The density of a substance is unique to it. Density is defined the as the amount of substance contained per volume.

One of the ways of identifying a substance is to determine its density. Every matter is known to have their own specific densities. This makes them different from other substances. The density of gold is unique to it and it differs from that of silver.

In fact, water has density of 1.00gcm⁻³. Experimental errors and some little factors must have altered our expected figure. This a case of precision and accuracy in the experiment.

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2 years ago

Initially, a particular sample has a total mass of 200 grams and contains 128 x 1010 radioactive nuclei. These radioactive nucle

lubasha [3.4K]

Explanation:

Formula to calculate how many particles are left is as follows.

N = $N_{0} (\frac{1}{2})^{l}$

where, $N_{0}$ = number of initial particles

l = number of half lives

As it is given that number of initial particles is $128 \times 10^{10}$ and number of half-lives is 3.

Hence, putting the given values into the above equation as follows.

N = $N_{0} (\frac{1}{2})^{l}$

= $128 \times 10^{10}(\frac{1}{2})^{3}$

= $16 \times 10^{10}$

or, $1.6 \times 10^{11}$

Thus, we can conclude that $1.6 \times 10^{11}$ particles of radioactive nuclei remain in the given sample.

In five hours we've gone through 5 half lives so the answer is:

particles

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3 years ago

How many moles of O2 are required to react with 6.6 moles of H2?

Bingel [31]

<u>Answer: </u>

<u>For 1:</u> 3.3 moles of oxygen gas is required.

<u>For 2:</u> 14 moles of hydrogen gas is required.

<u>For 3:</u> 1.5 moles of oxygen gas is required.

<u>Explanation:</u>

The chemical reaction of oxygen and hydrogen to form water follows:

$O_2+2H_2\rightarrow 2H_2O$

<u>For 1:</u> When 6.6 moles of $H_2$ is reacted.

By Stoichiometry of the above reaction:

2 moles of hydrogen gas reacts with 1 mole of oxygen gas.

So, 6.6 moles of hydrogen gas will react with = $\frac{1}{2}\times 6.6=3.3mol$ of oxygen gas.

Hence, 3.3 moles of oxygen gas is required.

<u>For 2:</u> When 7.0 moles of $O_2$ is reacted.

By Stoichiometry of the above reaction:

1 mole of oxygen gas reacts with 2 moles of hydrogen gas.

So, 7 moles of oxygen gas will react with = $\frac{2}{1}\times 7=14mol$ of hydrogen gas.

Hence, 14 moles of hydrogen gas is required.

<u>For 3:</u> When 3.0 moles of $H_2O$ is formed.

By Stoichiometry of the above reaction:

2 moles of water is formed from 1 mole of oxygen gas.

So, 3.0 moles of water will be formed from = $\frac{1}{2}\times 3.0=1.5mol$ of oxygen gas.

Hence, 1.5 moles of oxygen gas is required.

7 0

2 years ago

10.Give an example of an adaptation in birds, where shape of beak is related to the eating habits of that bird.

iVinArrow [24]

Answer:

It isn't only for the eating habits but also for building nests, hunting small insects, birds, other creatures including defence. Birds have a narrow small throat so the beak helps ripping off small peices of a big animal l(small bird) and for insects they crush and swallow it, they se their beak for feeding their children by grinding food in their beak and transferring it to the youngsters mouth

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2 years ago

When calcium plus iron oxide forms calcium oxide and iron, it is a ____________.

Jet001 [13]

Answer:

your answer is single replacement reaction or ay+b----> by+a

4 0

1 year ago