PLZZ!!!- I NEED THIS RIGHT NOWA block is pulled 0.90 m to the right in 2.5 s.

The energy difference between the 5d and 6s sublevels in gold accounts for its color. Assuming this energy difference is about 2

sergejj [24]

Answer:

$\lambda=459.1\times 10^{-7}\ m$ = 459.1 nm

This wavelength corresponds to yellow color and thus gold has warm yellow color.

Explanation:

Given that:- Energy = 2.7 eV

Energy in eV can be converted to energy in J as:

1 eV = 1.602 × 10⁻¹⁹ J

So, Energy = $2.7\times 1.602\times 10^{-19}\ J=4.33\times 10^{-19}\ J$

Considering:-

$E=\frac{h\times c}{\lambda}$

Where,

h is Plank's constant having value $6.626\times 10^{-34}\ Js$

c is the speed of light having value $3\times 10^8\ m/s$

$\lambda$ is the wavelength of the light

So,

$4.33\times 10^{-19}=\frac{6.626\times 10^{-34}\times 3\times 10^8}{\lambda}$

$4.33\times \:10^{26}\times \lambda=1.99\times 10^{20}$

$\lambda=459.1\times 10^{-7}\ m$ = 459.1 nm

This wavelength corresponds to yellow color and thus gold has warm yellow color.

7 0

1 year ago

A 75 lb (34 kg) boy falls out of a tree from a height of 10 ft (3 m). i. What is the kinetic energy of the boy when he hits the

Jobisdone [24]

Answer:

Kinetic energy of boy just before hitting the ground is $\approx$ 1000 J.

Speed of boy just before hitting the ground is 7.67 m/s

or 17.16 mi/hr.

Explanation:

Given that:

Mass of boy = 75lb = 34 kg

Height, h = 10ft = 3m

To find:

Kinetic energy of boy when he hits the ground.

As per law of conservation of energy The potential energy gets converted to kinetic energy.

$\therefore$ Kinetic energy at the time boy hits the ground = Initial potential energy of the boy when he was at the Height 'h'

The formula for potential energy is given as:

$PE = mgh$

Where m is the mass

g is the acceleration due to gravity, g = 9.8 $m/s^2$

h is the height of object

Putting all the values:

PE = $34 \times 9.8 \times 3 \approx 1000\ J$

Hence, Kinetic energy is $\approx$ 1000 J.

Formula for Kinetic energy is:

$KE = \dfrac{1}{2}mv^2$

where m is the mass and

v is the speed

Putting the values and finding v:

$1000 = \dfrac{1}{2}\times 34 \times v^2\\\Rightarrow v^2 = 58.82\\\Rightarrow v = 7.67\ m/s$

Given that:

1 m = 1.094 yd and 1 mi = 1760 yd

$\Rightarrow 1609\ m = 1\ mi$

Converting 7.67 m/s to miles/hour:

$\dfrac{7.67 \times 3600}{1609}=17.16\ mi/h$

4 0

2 years ago

How many grams of copper (II) nitrate would be produced from 0.80 g of copper metal reacting with excess nitric acid?

zaharov [31]

Answer:

$m_{Cu(NO_3)_2}=2.36 gCu(NO_3)_2$

Explanation:

Hello!

In this case, since the chemical reaction between copper and nitric acid is:

$2HNO_3+Cu\rightarrow Cu(NO_3)_2+H_2$

By starting with 0.80 g of copper metal (molar mass = 63.54 g/mol) and considering the 1:1 mole ratio between copper and copper (II) nitrate (molar mass = 187.56 g/mol) we can compute that mass via stoichiometry as shown below:

$m_{Cu(NO_3)_2}=0.80gCu*\frac{1molCu}{63.54gCu} *\frac{1molCu(NO_3)_2}{1molCu} *\frac{187.56gCu(NO_3)_2}{1molCu(NO_3)_2} \\\\m_{Cu(NO_3)_2}=2.36 gCu(NO_3)_2$

However, the real reaction between copper and nitric acid releases nitrogen oxide, yet it does not modify the calculations since the 1:1 mole ratio is still there:

$4HNO_3+Cu\rightarrow Cu(NO_3)_2+2H_2O+2NO_2$

Best regards!

7 0

2 years ago

If 15.6 g of hydrate are heated and only 11.7 g of anhydrous salt remain, calculate the % of water lost.

Elodia [21]

Answer:

Percent loss of water = 25%

Explanation:

Given data:

Mass of hydrated salt = 15.6 g

Mass of anhydrous salt = 11.7 g

Percentage of water lost = ?

Solution:

First of all we will calculate the mass of water in hydrated salt.

Mass of water = Mass of hydrated salt - Mass of anhydrous salt

Mass of water = 15.6 g - 11.7 g

Mass of water = 3.9 g

Now we will calculate the percentage.

Percent loss of water = mass of water / total mass × 100

Percent loss of water = 3.9 g/ 15.6 g × 100

Percent loss of water = 25%

8 0

2 years ago

Which of the following statements best describes the properties of aluminum-28?

Contact [7]

d. When aluminum-28 undergoes beta decay, silicon-28 is produced.

Explanation:

When the nuclei of aluminium-28 decays, it produces silicon- 28:

Aluminium ²⁸₁₃Al

Silicon 28 ²⁸₁₄Si

beta particle ⁰₋₁ $\beta$

²⁸₁₃Al → ²⁸₁₄Si + ⁰₋₁ $\beta$

This way, the mass and atomic number are conserved.

Conservation of mass number:

28 = 28 + 0, 28 = 28

13 = 14 -1 , 13 = 13

Learn more:

Balancing nuclear equations brainly.com/question/10094982

#learnwithBrainly

5 0

2 years ago