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Marina86 [1]
3 years ago
13

Which explains how burning a magnesium ribbon highlights a toolmark?

Chemistry
1 answer:
Setler [38]3 years ago
6 0
<h2>Answer:</h2>

The magnesium ribbon, <u>D. It forms a material to cast the tool mark</u>.

<h2>Explanation:</h2>

When a magnesium ribbon is burnt in the presence of oxygen it gives out strong light and heat is produced. Apart from it, it leads to the production of substance called as magnesium oxide which is formed as the product due to the reaction of magnesium with the oxygen present in the air.

Tool marks are the mark which is created by tools while using them. In order to identify or locate them castes made up of magnesium oxide is utilized. When this is pasted on the suspected area, the tool mark of the suspected tool gets pasted on it.

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Do all objects emit electromagnetic waves?
kherson [118]

Answer:

no, not all objects emit electromagnet waves.

Explanation: because lets say the object is carpet it has no magnetic waves in it so not all objects do.

6 0
3 years ago
in the following reaction, how many grams of benzene (C6H6) will produce 42 grams of CO2? 2C6H6 + 15O2 → 12CO2 + 6H2O
Mrrafil [7]

Answer: -

12.41 g

Explanation: -

Mass of CO₂ = 42 g

Molar mass of CO₂ = 12 x 1 + 16 x 2 = 44 g / mol

Number of moles of CO₂ = \frac{42}{44 g/mol}

= 0.9545 mol

The balanced chemical equation for this process is

2C₆H₆ + 15O₂ → 12CO₂ + 6H₂O

From the balanced chemical equation we see

12 mol of CO₂ is produced from 2 mol of C₆H₆

0.9545 mol of CO₂ is produced from \frac{2 mol C6H6 x 0.9545 mol  CO2}{12 mol CO2}

= 0.159 mol of C₆H₆

Molar mass of C₆H₆ = 12 x 6 + 1 x 6 =78 g /mol

Mass of C₆H₆ =Molar mass x Number of moles

= 78 g / mol x 0.159 mol

= 12.41 g

8 0
3 years ago
SEP Develop Models Each helium atom has two protons. Sketch models
RSB [31]

Protons and neutrons are located in the nucleus of the atom while the electrons move in the trajectory of the shell

<h3>Further explanation   </h3>

Isotopes are atoms whose no-atom has the same number of protons while still having a different number of neutrons.  

So Isotopes are elements that have the same Atomic Number (Proton)  

Isotopes of Helium : helium-3 and helium-4

  • ₂³He :

protons = 2

electrons=protons=2

neutron=mass number-atomic number=3-2=1

  • ₂³He :

protons = 2

electrons=protons=2

neutron=mass number-atomic number=3-2=1

  • ₂⁴He

protons = 2

electrons=protons=2

neutron=mass number-atomic number=4-2=2

Protons and neutron in the nucleus, electrons in the shell

6 0
3 years ago
From 1962 until 1981 pennies were made from 95% copper and 5% zinc and had a mass of 3.1 g. Starting in 1982, pennies have been
Sloan [31]

Answer:

2.7724 g

Explanation:

Mass of pre- 1892 pennies = 3.1 g

Abundance = 45.4 %

Mass of post 1892 pennies = 2.5 g

Abundance = 100 - 45.4 = 54.6 %

The average mass is given as = ( 3.1 g   *  45.4 / 100)  +  (2.5g  *  54.6 / 100)

Average Mass = 3.1 * 0.454   +   2.5  *  0.546

Average Mass = 1.4074  + 1.365 = 2.7724 g

8 0
3 years ago
Which of the following gases effuses the fastest at a given temperature?
Sholpan [36]

Answer: -

H₂ will diffuse the fastest.

Explanation: -

According to Graham's Law of Diffusion

The rate of diffusion is inversely proportional to the square root of it's density or molar mass. So the lower the molar mass faster the rate of diffusion.

Molar mass of Ne = 20 g / mol

Molar mass of CH₄ = 12 x 1 + 1 x 4 = 16 g /mol

Molar mass of Ar = 40g / mol

Molar mass of H₂ = 1 x 2 = 2 g / mol

Thus H₂ will diffuse the fastest.

7 0
3 years ago
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