What’s the equation for

1) When elements combine to form compounds:

vodomira [7]

Answer:

B

Explanation:

when elements reacts to form a compound the elements properties changes completely. This happens due to the fact that a chemical reaction has taken place. In a chemical change new substances are formed and the properties of the products differ entirely from that of the reactant.

for example if hydrogen combines with oxygen to form water, the property of hydrogen differs from oxygen and also both differs chemically when compared to water.

6 0

4 years ago

How much energy is released by the decay of 3 grams of 20Th in the following reaction 230 Th - 226Ra + 'He (230 Th = 229.9837 g/

wolverine [178]

Answer : The energy released by the decay of 3 grams of 'Th' is $2.728\times 10^{-15}J$

Explanation :

First we have to calculate the mass defect $(\Delta m)$ .

The balanced reaction is,

$^{230}Th\rightarrow ^{226}Ra+^{4}He$

Mass defect = Sum of mass of product - sum of mass of reactants

$\Delta m=(\text{Mass of Ra}+\text{Mass of He})-(\text{Mass of Th})$

$\Delta m=(225.9771+4.008)-(229.9837)=1.4\times 10^{-3}amu=2.324\times 10^{-30}kg$

conversion used : $(1amu=1.66\times 10^{-27}kg)$

Now we have to calculate the energy released.

$Energy=\Delta m\times (c)^2$

$Energy=(2.324\times 10^{-30}kg)\times (3\times 10^8m/s)^2$

$Energy=2.0916\times 10^{-13}J$

The energy released is $2.0916\times 10^{-13}J$

Now we have to calculate the energy released by the decay of 3 grams of 'Th'.

As, 230 grams of Th release energy = $2.0916\times 10^{-13}J$

So, 3 grams of Th release energy = $\frac{3}{230}\times 2.0916\times 10^{-13}J=2.728\times 10^{-15}J$

Therefore, the energy released by the decay of 3 grams of 'Th' is $2.728\times 10^{-15}J$

5 0

4 years ago

Unemployment rate varies according to such factors as

sineoko [7]

I’m pretty sure the answer is A.

3 0

3 years ago

A change in the properties of matter that does not change the identity of the substance is:

Ugo [173]

No, the correct answer is B. Physical change because the identity of the substance does not change.
For example, if you take a piece of paper and tear it in half you actually changed its property because now those pieces of paper have half the weight and and size that they did before you did anything. Now you know its a physical change because its still paper all you have done is change the physical appearance.
Hope this was helpful(;

6 0

4 years ago

Read 2 more answers

In terms of drug development, rank the following microbes from most difficult (1) to least difficult (3):

iVinArrow [24]

Answer:

See below ↓↓↓

Explanation:

Helminths = 1 Most Difficult

Fungi = 2 Moderately Difficult [Option not given, but 2 is right answer]

Bacteria = 3 Least Difficult

6 0

2 years ago