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Marina86 [1]
2 years ago
9

An envelope could be a source of DNA evidence. True False

Chemistry
2 answers:
yuradex [85]2 years ago
7 0

Answer:

True

Explanation:

DNA can be extracted from bite marks, cigarette buds, postage stamps on envelopes, and envelope flaps for DNA analysis.

Wewaii [24]2 years ago
6 0

Answer:

false. a envelope is what the DNA evidence goes in

Explanation:

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When octane (C8H18) is burned in the presence of oxygen, the yield of products (carbon dioxide and water) is 87%. What mass of c
ahrayia [7]

Answer:

14.5g of CO₂ are produced

Explanation:

The reaction of octane with oxygen is:

C₈H₁₈ + 25/2O₂ → 8CO₂ + 9H₂O

<em>Where 1 mole of octane (Molar mass: 114.23g/mol) reacts with 25/2 moles of O₂ (Molar mass 32g/mol) to produce 8 moles of CO₂ and 9 moles of water.</em>

When 21.0 g of octane is burned with 19.0 g of oxygen gas you need to find <em>limiting reactant </em>to find how many moles of products are formed:

Octane: 21.0g ₓ (1mol / 114.23g) = 0.184 moles octane

Oxygen: 19.0g ₓ (1 mol / 32g) = 0.594 moles oxygen

For a complete reaction of 0.184 moles of octane you will need:

0.184 moles C₈H₁₈ ₓ (25/2 moles O₂ / 1 mole C₈H₁₈) = <em>2.3 moles of oxygen</em>

As you have just 0.594 moles of oxygen, <em>Oxygen is limiting reactant.</em>

Based on chemical equation, 25/2 of O₂ produce 8 moles of CO₂, that means theoretical yield of CO₂ with 0.594 moles of O₂ is:

0.594 moles O₂ ₓ (8 moles CO₂ / 25/2 moles O₂) = 0.380 moles of CO₂

But, as yield of products is 87%, moles produced of CO₂ are:

0.380 moles of CO₂ ₓ 87% = 0.331 moles CO₂ are produced.

As molar mass of CO₂ is 44g/mol, mass of CO₂ in 0.331 moles is:

0.331 moles CO₂ ₓ (44g / mol) =

<h3>14.5g of CO₂ are produced</h3>
6 0
2 years ago
How can electronegativity be used to explain the reaction we see in terms of the numbers and types of bonded being formed in lit
kolezko [41]

Explanation:

Lithium is an electropositive element that readily loses electrons.

Oxygen is electronegative and it will readily accept electrons.

 Due to this significant electronegativity differences between the two species they form electrovalent or ionic bonds between them.

  2atoms of Li lose two electrons:

      Li  →  Li²⁺ + e⁻

             Lithium isoelectronic with helium

 For oxygen;

      O + 2e⁻   →  O²⁻

                          Oxygen is isoelectronic with Neon

Two ions of the lithium combines with the oxygen to form the bond;

                   4Li + O₂  →  2Li₂O

The electrostatic attraction between the two ions forms the ionic bond

5 0
3 years ago
Which are balanced plus if they aren’t please correct them
Veronika [31]

b,f,h are already balanced

7 0
3 years ago
Calculate the density of an object with a mass of 30g and volume of 6cm^3
Kipish [7]
Density = Mass ÷ Volume

D= 30g ÷ 6 cm^3

D= 5 g/dm^3

3 0
3 years ago
What is the kinetic energy of a 10 kg object that has a velocity of 1.5 m/s
katen-ka-za [31]

Answer: 11.25 J

Explanation: Kinetic energy is expressed as the product of mass and the squared of velocity divided by 2.

3 0
3 years ago
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