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Gelneren [198K]
4 years ago
13

Which elements are metalloids

Physics
1 answer:
zhannawk [14.2K]4 years ago
7 0

The six commonly recognised metalloids are boron, silicon, germanium, arsenic, antimony, and tellurium....

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If an unknown element has a mass of 17 and contains 6 neutrons, how many protons does it have ?
lbvjy [14]

The mass number is the total number of protons and neutrons within an atom and since we know that the unknown element has 6 neutrons, we can simply subtract the number of neutrons from the mass number to get the number of protons.

17 - 6 = 11

There are 11 protons in this unknown element.


Extra:

The number of protons (+) and electrons (-) are equal in a neutral atom so since you know that there are 11 protons you also know that there are 11 electrons. On the periodic table, the element with 11 electrons is Na or Sodium.


Hope this helps! :)

6 0
3 years ago
According to the graph, how many atoms would remain after two half-lives?
Fudgin [204]

Answer:

Let No be initial no of atoms

N = N0 / 2      after 1 half-life

N = N0 / 4     after 2 half-lives

So after 2 half-lives 20 of the 80 atoms remain

4 0
3 years ago
An engine has an energy input of 125j and 35 j of that energy is transformed into useful energy
Tatiana [17]
The engine's efficiency is (35J)/125J) = 28% .

Do you have a different question to ask ?
5 0
3 years ago
You are designing a simple elevator system for an old warehouse that is being converted to loft apartments. A 22,500-N elevator
ICE Princess25 [194]

Answer:

A) mass = 3121.58 kg

B) tension = 25940.37 N

C) tension = 25940.37 N (tension on both sides will be the same)

Explanation:

Weight of elevator = 22500 N

Distance = 6.75 m

Time = 3 sec

Since it started from rest, initial speed is zero.

Using Newton's equation of motion we have,

S = ut + 0.5at^2

S = distance covered = 6.75 m

t = time = 3 s

a = acceleration upwards

u = initial velocity = 0

Substituting values, we have,

6.75 = 0(3) + (0.5 x a x 3^2)

6.75 = 4.5a

a = 6.75/4.5 = 1.5 m/s^2 (acceleration of the elevator upwards)

Mass of the elevator = Weight/g

Where g = acceleration due to gravity 9.81 m/s

Mass = 22500/9.81 = 2293.58 kg

From the image below we solve from

T - 22500 = ma

T - 22500 = 2293.58 x 1.5

T - 22500 = 3440.37

T = 3440.37 + 22500 = 25940.37 N (this is the tension on the rope)

On the other side,

mg - T = ma

9.81m - 25940.37 = 1.5m

(9.81 - 1.5)m = 25940.37

8.31m = 25940.37

m = 3121.58 kg (mass of counter weight)

See image below

8 0
3 years ago
Where does the energy that is used to ride a bicycle up a hill come from and how is it classified?
MariettaO [177]
Well when you eat you get energy and then you use it to ride up the hill sorry I don't know how it is classified
7 0
3 years ago
Read 2 more answers
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