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Vera_Pavlovna [14]
3 years ago
8

Select all the correct answers,

Chemistry
1 answer:
Anastasy [175]3 years ago
7 0

Answer:

The reaction for which ΔH is positive are endothermic reactions.

Explanation:

The energy changes occur during the bonds formation and bonds breaking.

There ere two types of reaction endothermic and exothermic reaction.

Endothermic reactions:

The type of reactions in which energy is absorbed are called endothermic reactions.

In this type of reaction energy needed to break the bond are higher than the energy released during bond formation.

For example:

C + H₂O   →  CO  + H₂

ΔH = +131 kj/mol

it can be written as,

C +  H₂O  + 131 kj/mol  →  CO  + H₂

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36) What is the mass of a 4.259 g/cm substance which takes up 250.00 cm of space?
Hunter-Best [27]

Answer:

<h3>The answer is 1064.75 g</h3>

Explanation:

The mass of a substance when given the density and volume can be found by using the formula

<h3>mass = Density × volume</h3>

From the question

volume of substance = 250 cm³

density = 4.259 g/cm³

We have

mass = 4.259 × 250

We have the final answer as

<h3>1064.75 g</h3>

Hope this helps you

7 0
3 years ago
The use of fertilizers in agriculture has significantly altered several nutrient cycles including:
Lana71 [14]

Answer:

potassium, nitrogen and phosphorous cycle

Explanation:

A fertilizer is a substance which is applied on the plants by farmers to increase the supply of nutrients for the plants. Fertilizers have known to be toxic in many ways such as they alter the potassium, nitrogen and phosphorus cycles. Nitrogen, potassium and phosphorus are present in abundant amounts in the fertilizers. Draining of these fertilizers into rivers and ponds is toxic for the aquatic life. Hence, the use of fertilizers disrupts the natural cycles and is toxic for many aquatic plants and animals.

4 0
3 years ago
Will hydrogen ever make a double bond?
Andrei [34K]
No, hydrogen can only hold one bond and that's it.  It only needs to be paired with one bond.  
7 0
3 years ago
Read 2 more answers
One crystalline form of silica (SiO2) has a cubic unit cell, and from X-ray diffraction data it is known that the cell edge leng
tigry1 [53]

Answer:

There are 8Si atoms and 16 O atoms per unit cell

Explanation:

From the question we are told that:

Edge length l=0.700nm=>0.7*10^9nm

Density \rho=2.32g/cm^3

Generally the equation for Volume is mathematically given by

V=l^3

V=(0.7*10^9)m^3

V=3,43*10^-{22}cm

Where

Molar mass of  (SiO2) for one formula unit

M=28+32

M=60g/mol

Therefore

Density of Si per unit length is

\rho_{si}=\frac{9.96*10^{23}}{3.43*10^22}

\rho=0.29

Molar mass of  (SiO2) for one formula unit

M=28+32

M=60g/mol

Therefore

There are 8Si atoms and 16 O atoms per unit cell

6 0
3 years ago
The volume of a sample of gas measured at 35 C and 1.00 atm pressure is 2.00 L. What must the final temperature be in order for
____ [38]

Answer:

the final temperature is 465.2k

6 0
2 years ago
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