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3 years ago

Round 23.455 cm into 4 significant figures

2 answers:

4 0

It would be 23.46, since the next number is a 5 so we can round up.

Significant figures are:
ANY number that is not 0
Any 0 between two nonzero digits
Any 0 following a decimal (i.e 1.50)

cluponka [151]3 years ago

4 0

Answer:

23.46

Explanation:

Significant figures are the number of digits or the numbers that contribute to the actual value of a measurement.

Some of the rules to check the number of significant figures are:

- All non-zero digits are always significant

-Zeros in between numbers are significant

-Leading zeros after decimal are not significant

-Trailing zeros after decimal are significant

-If the final digit after decimal is greater than or equal to 5, it can be rounded up to the next higher number

The given value is:

23.455 it has 5 significant figures

Rounding up (since the last digit = 5) to 4 significant figures gives:

23.46

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A sample of a pure element has a mass of 45.6g and contains 4.19 x 10 23 atoms. Identify the element.

max2010maxim [7]

<h2>Answer:</h2>

ZINC

<h2>Explanation:</h2>

To identify the element based on the informartion given, we have to find the molar mass since this mass is unique to each element.

Molar mass = mass ÷ moles

We already know the mass based on the question, as such we now need to find the # of moles.

Since 1 mole contains 6.02214 × 10²³ atoms

then let x moles contain 4.19 × 10²³ atoms (given in the question)

  ⇒ x = (4.19 × 10²³ atoms × 1 mol) ÷ 6.02214 × 10²³ atoms

x = 0.69577 mol

Now that we have the moles we can substitute it into the molar mass equation and solve for the molar mass.

⇒ molar mass = 45.6 g ÷ 0.69577 mol

⇒ molar mass ≈ 65.54 g/mol

This molar mass is closest to that of ZINC.

7 0

2 years ago

Makovka662 [10]

Answer:

1) 70

2) conduction

3) The ground absorbs the solar radiation and

releases it throughout the later afternoon.

4) transpiration

5) convection

6) cumulonimbus

7) reflectivity of Earth’s surface

8) As temperature increases, air pressure

increases.

9) thermosphere

10) convection cells, pressure belts, and the

Coriolis effect

11) radiation

12) pollen

13) scattering

14) thermosphere

15) The different types of clouds are:

cumulus: Cumulus clouds are clouds which have flat bases and are often described as "puffy", "cotton-like" or "fluffy" in appearance. Their name derives from the Latin cumulo-, meaning heap or pile.

cirrus: Cirrus is a genus of atmospheric cloud generally characterized by thin, wispy strands, that typically appear white or light grey. The name is derived from the Latin word cirrus, meaning 'ringlet' or 'curling lock of hair'. Such a cloud can form at any altitude between 5,000 and 13,700 m above sea level.

stratus: Stratus clouds are low-level clouds characterized by horizontal layering with a uniform base, as opposed to convective or cumuliform clouds that are formed by rising thermals.

nimbus: Nimbostratus clouds are dark, grey, featureless layers of cloud, thick enough to block out the Sun and produce persistent rain. Height of base: 2,000 - 10,000 ft. Shape: Bands or areas of individual cells. Latin: nimbus - rainy cloud; stratus - flattened or spread out. Precipitation: Continuous rain or snow likely.

16) the tradewinds

17) the location’s latitude

18) Cirrus clouds

19) the ozone layer

20) Global winds are created by both the spin of

the Earth (Coriolis effect) and the differences

in temperature between the equator and

the polar areas. These winds are often

grouped together as trade winds, easterlies,

and westerlies.

21) nitrogen

22) the Miller-Urey hypothesis

the Oparin-Haldane hypothesis

23) ammonia gas

24) cumulus

25) It determines the mass of water in a volume of air

Explanation:

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7 0

2 years ago

Fe2O3+2Al=Al2O3+2Fe

True [87]

We determine the limiting reactant by using the moles present in the equation and the actual moles.
According to equation, ratio of Fe₂O₃ : Al = 1 : 2
Actual moles of Fe₂O₃ = 187.3 / (56 x 2 + 16 x 3)
= 1.17
Actual moles of Al = 94.51 / 27
= 3.5
Fe₂O₃ is limiting. Fe₂O₃ required:
(moles Al)/2 = 3.5/2 = 1.75
Moles to be added = 1.75 - 1.17
= 0.58
Mass to be added = moles x Mr
= 0.58 x (56 x 2 + 16 x 3)
= 92.8 grams

6 0

2 years ago

Read 2 more answers

you fill a rigid steel container that has a volume of 20 L with nitrogen gas to a final pressure of 2 x 10^4 kpa at 23 Celsius.

garik1379 [7]

Answer:

4.549 kg.

Explanation:

We can use the general law of ideal gas: PV = nRT.

where, P is the pressure of the gas in atm (P = 2 x 10⁴ kPa/101.325 = 197.4 atm).

V is the volume of the gas in L (V = 20.0 L).

n is the no. of moles of the gas in mol (n = ??? mol).

R is the general gas constant (R = 0.0821 L.atm/mol.K),

T is the temperature of the gas in K (T = 23° C + 273 = 296 K).

∴ n = PV/RT = (197.4 atm)(20.0 L)/(0.0821 L.atm/mol.K)(296 K) = 162.5 mol.

To find the mass of N₂ in the cylinder, we can use the relation:

mass of N₂ = (no. of moles of N₂)*(molar mass of N₂) = (162.5 mol)*(28.0 g/mol) = 4549 g = 4.549 kg.

3 0

2 years ago

What determines the amount of energy an electron has?

Natalka [10]

Answer:

The energy of an electron in many–electron atom is determined by both principal quantum number (n) and azimuthal quantum number (l)

8 0

2 years ago