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3 years ago

Why are fixed resistors’ values indicated by color bands rather than printing the numeric value on their exterior?

1 answer:

6 0

Because there are so many different values of numbers, it would be impractical to use 1Ω, 2Ω, 3Ω... etc... Using colored bands helps make reading it a little easier to the trained eye. There are hundreds of thousands, if not tens of millions of different resistors would need to exist to cover every value. So you just use something called "preferred values" with their resistance values posted on them instead.

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What is the molarity of a 0.250 L MgCl2 solution that contains 0.175 mol MgCl2?

spayn [35]

Explanation:

we know that 0.250 L = 0.250 dm3

molarity = concentration in dm3/ volume

molarity = 0.175/0.250 = 0.7 mol/dm3

4 0

2 years ago

Write the charge and full ground-state electron configuration of the monatomic ion most likely to be formed by each:

Sladkaya [172]

Answer:

Part A:

Charge is $P^{3-}$

Configuration is $1s^2 2s^22p^63s^23p^6$

Part B:

Charge is $Mg^{2+}$

Configuration is $1s^2 2s^22p^6$

Part C:

Charge is $Se^{2-}$

Configuration is $1s^2 2s^22p^63s^23p^64s^23d^{10}4p^6$

Explanation:

Monatomic ions:

These ions consist of only one atom. If they have more than one atom then they are poly atomic ions.

Examples of Mono Atomic ions: $Na^+, Cl^-, Ca^2^+$

Part A:

For P:

Phosphorous (P) has 15 electrons so it require 3 more electrons to stabilize itself.

Charge is $P^{3-}$

Full ground-state electron configuration of the mono atomic ion:

$1s^2 2s^22p^63s^23p^6$

Part B:

For Mg:

Magnesium (Mg) has 12 electrons so it requires 2 electrons to lose to achieve stable configuration.

Charge is $Mg^{2+}$

Full ground-state electron configuration of the mono atomic ion:

$1s^2 2s^22p^6$

Part C:

For Se:

Selenium (Se) has 34 electrons and requires two electrons to be stable.

Charge is $Se^{2-}$

Full ground-state electron configuration of the mono atomic ion:

$1s^2 2s^22p^63s^23p^64s^23d^{10}4p^6$

8 0

3 years ago

if an element [x] contains 8 protons, 8 neutrons and 8 electrons, the atomic number of the element is ?

Kaylis [27]

Answer:

Explanation:

The atomic number refers to the number which identifies the element, which is the proton number.

7 0

2 years ago

Find the mass of 0.235 moles of SiO2? (NOTE: use correct significant figures!)

marta [7]

Answer: 14.1g

Explanation:

Given that,

number of moles of SiO2 = 0.235 moles

Mass in grams = Z (let unknown value be Z)

Molar mass of SiO2 = ?

To get the molar mass of SiO2, use the atomic mass

Silicon = 28g;

Oxygen = 16g

i.e Molar mass of SiO2 = 28g + (16g x 2)

= 28g + 32g

= 60g/mol

Now, apply the formula

Number of moles = Mass / molar mass

0.235 moles = Z / 60g/mol

Z = 0.235 moles x 60g/mol

Z = 14.1 g

Thus, the mass of SiO2 is 14.1 grams.

8 0

2 years ago

How are acids and bases defined by bronsted lowry?

lesantik [10]

A Bronsted-Lowry acid is a chemical species that donates one or more hydrogen ions in a reaction. In contrast, a Bronsted-Lowry base accepts hydrogen ions. When it donates its proton, the acid becomes its conjugate base. A more general look at the theory is as an acid as a proton donor and a base as a proton acceptor. :)

4 0

3 years ago