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stich3 [128]
4 years ago
14

Which material can best be used to cast a footwear or tire impression?

Chemistry
1 answer:
mixer [17]4 years ago
5 0

Answer:

B.) cement

Explanation:

The commonest types of impression evidence found in crime scenes include footprints, tire tracks, bite marks and tool marks etc.These types of impression evidence can be used by crime scene investigators to link the suspects to the crime.

The impressions are usually cast using gypsum cement and other forms of casting tools to preserve the evidence and make it useful during any period in the course of the investigation.

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Nitric acid is a key industrial chemical, largely used to make fertilizers and explosives. The first step in its synthesis is th
kolbaska11 [484]

Answer: When using 645 L /s  of O2 in a temperature and pressure of  195°C,  0.88 atm  respectively, we will get 0.355Kg /s NO

Explanation:

  • First we review the equation that represents the oxidation process of the NH3 to NO.

4NH3(g) + 5O2(g) ⟶4 NO(g) +6 H2O(l)  

  • Second we gather the information what we are going to use in our calculations.

O2 Volume Rate = 645 L /s

Pressure = 0.88 atm

Temperature = 195°C + 273 = 468K

NO molecular weight = 30.01 g/mol  

  • Third, in order to calculate the amount of  NO moles produced by 645L/ s of O2, we must find out, how many moles (n) are 645L O2 by using the general gas equation PV =n RT

Let´s keep in mind that using this equation our constant R is 0.08205Lxatm/Kxmol

PV =n RT

n= PV / RT

n= [ 0.88atm x 645L/s] / [ (0.08205 Lxatm/Kxmol) x 468K]

n= 14.781 moles /s of O2

  • Fourth, now by knowing the amount of moles of O2, we can use the equation to calculate how many moles of NO will be produced and then with the molecular weight, we will finally know the total mass per second .

14.781 moles /s of O2 x 4moles NO / 5 moles O2 x  30.01g NO / 1 mol NO x 1Kg NO /1000g NO = 0.355Kg /s NO

6 0
3 years ago
Plz help me i have to give this by today pls...........
vfiekz [6]
I need a a picture or the question
7 0
3 years ago
HELP PLEASE!!! FIRST PERSON TO ANSWER GETS 90 POINTS AND MARKED BRAINLIEST!
3241004551 [841]

Answer:

MgO has a highest melting point

C5Br has lowesst

Explanation:

It takes a lot of energy to overcome the strong electrostatic forces of attraction between oppositely charged ions, so ionic compounds have high melting and boiling points. ... Magnesium oxide is made from ions with two charges (Mg 2+ and O 2-) and so has a much higher melting point of 2852°C.

3 0
3 years ago
If you took an empty balloon, weight it on a scale then filled the balloon up with air and weighed it again would you expect the
larisa [96]
Yes, because the balloon with air has a greater density than the empty balloon.Because there is a higher density in one balloon then the weight of the balloon will change
8 0
3 years ago
Activation energy Group of answer choices is only required in catabolic reactions that release energy. is not required at all wh
daser333 [38]

Answer:

is used to break reactant bonds and/or make new product bonds.

Explanation:

<em>The correct answer would be that </em><em>activation energy is used to break reactant bonds and/or make new product bonds</em><em>.</em>

The <u>activation energy is the minimum energy that must be overcome by the reactants in a reaction in other to become products</u>. In order for products to be formed, the bonds between reactants must be broken and new ones must be formed to arrive at the products. In other words, the activation energy can be seen as the energy required to break the bonds between reactants and form the bonds between products during the course of a reaction.

<em>Activation energy is required even in the presence of enzymes. The latter only catalyzes reactions by lowering the minimum energy required to break the bonds between reactants and form new ones between products</em>.

5 0
3 years ago
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