True or False. Ecosystems are always very large and cover a large amount of land.

Consider the following properties: I) The red color of rubies is due to the presence of chromium ions. II) Objects made of silve

quester [9]

Answer:

II) Objects made of silver become tarnished.

Explanation:

Physical properties are the properties which can be observed without changing identity of substance.

Chemical properties are the properties which describe how the substance changes into the different substance completely.

Boiling is an example of physical change in state of the substance. Color is also an example of physical property like boiling point and hence these are constants. The reason of the color is that the chromium ions shows certain colors as the electrons are excited due to absorption of the light. The tarnishing of the silver is an example of the chemical change which occurs due to the reaction of the silver with oxygen. This is also known as corrosion.

5 0

4 years ago

When a 32.3 g sample of NaI (Sodium Iodide) dissolves in 90.0 mL of water in a calorimeter, the temperature rises from 23.5 ℃ to

Leona [35]

Answer:

B

Explanation:

3 0

3 years ago

Write the chemical equation of in elements

Scilla [17]

Answer : The balanced chemical reaction will be:

$CuO+H_2SO_4\rightarrow CuSO_4+H_2O$

Explanation :

As per question when copper(II) oxide react with sulfuric acid then it gives copper(II) sulfate and water.

This reaction is known as double displacement reaction in which cation of two reactants exchange their places to give two different products.

The balanced chemical reaction will be:

$CuO+H_2SO_4\rightarrow CuSO_4+H_2O$

8 0

4 years ago

Line.

blagie [28]

Answer:

c) Normal

Explanation:

Reflection is a phenomenon typical of light wave; it occurs when a ray of light hits the interface between two mediums, and bounces off back into the original medium, at a certain angle.

The direction of the reflected ray is determined by the law of reflection, which states that:

1) The incident ray and the reflected ray, together with the normal to the interface (the perpendicular to the interface), all lie within the same plane

2) The angle of incidence is equal to the angle of reflection:

$\theta_i=\theta_r$

where

$\theta_i$ is measured as the angle between the incident ray and the normal to the interface

$\theta_r$ is measured as the angle between the reflected ray and the normal to the interface

8 0

4 years ago

f 65mL of sulfuric acid and 25mL of sodium hydroxide were mixed and the solution had a density of 1.01g/mL, what is the heat of

user100 [1]

The question is incomplete, here is the complete question:

If 65 mL of sulfuric acid and 25 mL of sodium hydroxide were mixed and the solution had a density of 1.01 g/mL, What is the heat of the calorimeter in kJ given the temperature change of the above equation is -5.5 K. You may assume the solution has a heat capacity of 4.180 J/gK. Express your final answer in kJ and with 2 decimal places

Answer: The heat of the calorimeter is 2.09 kJ

Explanation:

To calculate the mass of solution, we use the equation:

$\text{Density of substance}=\frac{\text{Mass of substance}}{\text{Volume of substance}}$

Density of solution = 1.01 g/mL

Volume of solution = [65 + 25] mL = 90 mL

Putting values in above equation, we get:

$1.01g/mL=\frac{\text{Mass of solution}}{90mL}\\\\\text{Mass of solution}=(1.01g/mL\times 90mL)=90.9g$

To calculate the heat released by the reaction, we use the equation:

$q=mc\Delta T$

where,

q = heat released

m = mass of solution = 90.9 g

c = heat capacity of solution = 4.180 J/g.K

$\Delta T$ = change in temperature = -5.5 K

Putting values in above equation, we get:

$q=90.9g\times 4.180J/g.K\times (-5.5K)=-2089.8J=-2.09kJ$

Heat released by the solution will be equal to the heat absorbed by the calorimeter.

Sign convention of heat:

When heat is absorbed, the sign of heat is taken to be positive and when heat is released, the sign of heat is taken to be negative.

Heat absorbed by the calorimeter = -(-2.09) = 2.09 kJ

Hence, the heat of the calorimeter is 2.09 kJ

8 0

4 years ago