All categories

2 years ago

I'm giving 20 points! please it's for a friend not me

Chemistry

1 answer:

astra-53 [7]2 years ago

6 0

Answer:

Three chemical elements: hydrogen, oxygen, and helium.

The difference between metals and metalloids is: metalloids have properties in between those of the metals and non-metals and are semiconductors.

The periodic table is organized by the elemts atomic number, it goes from the element with the lowest atomic number (which is hydrogen) to the element with the highest atomic number (oganesson)

Explanation:

Hope this helps :)

You might be interested in

The filling of which orbital is represented by the transition metals in period 4?

Sindrei [870]

Answer: 3d

Explantion:

1) Period 4 contains the elements with atomic numbers 19 through 36.

2) The elements with atomic numbers 19 (K) and 20 (Ca) fill the orbital 4s.

3) After that, as Aufbau's rule may help you to remember, the energy of the orbitals 3d is lower than the energy of the orbtitals 4p. So, the element 21 (Sc) start fillind the orbital 3d.

There are ten 3d orbitals, so the elements 21 through 30 fill the 3d orbitals.

Those elements, called transition metals are: Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, and Zn.

When the 3d orbitals are full, the next elements in the same period 4, fill the six 4p orbitals.

3 0

3 years ago

Read 2 more answers

Kc = 3.07 x 10-4 at 24°C for 2NOBr(g) ↔ 2NO(g) + Br2(g). If the initial concentration of NOBr = 0.878 M, what is the equilibrium

pav-90 [236]

Answer:

The equilibrium concentration of NO is 0.02124 M.

Explanation:

Given that,

Initial concentration of NOBr = 0.878 M

$k_{c}=3.07\times10^{-4}$

Temperature = 24°C

We know that,

The balance equation is

$2NOBr\Rightarrow 2NO+Br_{2}$

Initial concentration is,

$0.878\Rightarrow 0+0$

Concentration is,

$-2x\Rightarrow 2x+x$

Equilibrium concentration

$0.878-2x\Rightarrow 2x+x$

We need to calculate the value of x

Using formula of concentration

$k_{c}=\dfrac{[NO][Br_{2}]}{[NOBr]^2}$

Put the value into the formula

$3.07\times10^{-4}=\dfrac{[2x][x]}{[0.878-2x]^2}$

$2x^2=3.07\times10^{-4}\times(0.878)^2+3.07\times10^{-4}\times4x^2-2\times2x\times0.878\times3\times10^{-4}$

$2x^2=0.0002367+0.001228x^2-0.0010536x$

$2x^2-0.001228x^2+0.0010536x-0.0002367=0$

$1.998772x^2+0.0010536x-0.0002367=0$

$x=0, 0.01062$

We need to calculate the equilibrium concentration of NO

Using formula of concentration of NO

$concentration\ of\ NO=2x$

Put the value of x

$concentration\ of\ NO=2\times0.01062$

$concentration\ of\ NO=0.02124$

Hence, The equilibrium concentration of NO is 0.02124 M.

7 0

3 years ago

Which natural polymer makes up paper? A. starch B. nylon C. wool D. rubber

eduard

Answer:

starch

Explanation:

7 0

3 years ago

Calculate each of the following quantities:

notsponge [240]

Molarity of 275 mL of solution containing 135 mol of glucose.

<h3>What is molarity?</h3>

Molar concentration (also known as molarity, quantity concentration, or substance concentration) is a measure of the concentration of a chemical species in a solution, specifically of a solute, in terms of amount of substance per unit volume of solution. The most often used unit for molarity in chemistry is the number of moles per liter, denoted by the unit symbol mol/L or mol/dm3 in SI units. A solution with a concentration of 1 mol/L is referred to as 1 molar, or 1 M.

To learn more about molarity visit:

brainly.com/question/8732513

#SPJ4

4 0

1 year ago

A heterogeneous material may be

IgorLugansk [536]

Answer:

4) a mixture.....................

7 0

2 years ago

Read 2 more answers