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3 years ago

11

Why does ice float after it crystallizes? Its mass is greater than water. Its density is greater than water. Its density is less

than water. Air trapped in ice causes it to float.

2 answers:

lina2011 [118]3 years ago

8 0

Its density is less than water

tekilochka [14]3 years ago

7 0

Ice floats after it crystallizes because ITS DENSITY IS LESS THAN THAT OF WATER.

When a quantity of water is cools down by reducing its temperature, the molecules of the water lose kinetic energy and slow down in their movement. As the water is cooling down, it is volume is expanding. When the temperature reaches zero degree Celsius, the water becomes ice. At this point, the ice can float on water because its density is less than that of water; this is as a result of the spaces that now exist in the ice structure.

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In Philip’s French class, the students are learning how to pronounce closed vowels and open vowels. The students are most likely

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Answer:

It sounds like they are studying French phonemes

Explanations:

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3 years ago

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Describe why an element's physical properties are different from its chemical properties. Include in your answer an example of o

Contact [7]

Answer:

Explanation:

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At first, they differ because a physical property is observed without changing the nature of the substance. On the other hand, a change in the nature of the substance must be carried out to observe a chemical property.

As examples, density, solubility and odor (physical properties) could be known by just analyzing a substance, nonetheless, pH, reactivity or combustibility must be known by submitting the substance to a specific chemical reaction.

Best regards.

4 0

3 years ago

Determine Z and V for steam at 250°C and 1800 kPa by the following: (a) The truncated virial equation [Eq. (3.38)] with the foll

makvit [3.9K]

Answer:

Explanation:

Given that:

the temperature $T_1$ = 250 °C= ( 250+ 273.15 ) K = 523.15 K

Pressure = 1800 kPa

a)

The truncated viral equation is expressed as:

$\frac{PV}{RT} = 1 + \frac{B}{V} + \frac{C}{V^2}$

where; B = - $152.5 \ cm^3 /mol$ C = -5800 $cm^6/mol^2$

R = 8.314 × 10³ cm³ kPa. K⁻¹.mol⁻¹

Plugging all our values; we have

$\frac{1800*V}{8.314*10^3*523.15} = 1+ \frac{-152.5}{V} + \frac{-5800}{V^2}$

$4.138*10^{-4} \ V= 1+ \frac{-152.5}{V} + \frac{-5800}{V^2}$

Multiplying through with V² ; we have

$4.138*10^4 \ V ^3 = V^2 - 152.5 V - 5800 = 0$

$4.138*10^4 \ V ^3 - V^2 + 152.5 V + 5800 = 0$

V = 2250.06 cm³ mol⁻¹

Z = $\frac{PV}{RT}$

Z = $\frac{1800*2250.06}{8.314*10^3*523.15}$

Z = 0.931

b) The truncated virial equation [Eq. (3.36)], with a value of B from the generalized Pitzer correlation [Eqs. (3.58)–(3.62)].

The generalized Pitzer correlation is :

$T_c = 647.1 \ K \\ \\ P_c = 22055 \ kPa \\ \\ \omega = 0.345$

$T__{\gamma}} = \frac{T}{T_c}$

$T__{\gamma}} = \frac{523.15}{647.1}$

$T__{\gamma}} = 0.808$

$P__{\gamma}} = \frac{P}{P_c}$

$P__{\gamma}} = \frac{1800}{22055}$

$P__{\gamma}} = 0.0816$

$B_o = 0.083 - \frac{0.422}{T__{\gamma}}^{1.6}}$

$B_o = 0.083 - \frac{0.422}{0.808^{1.6}}$

$B_o = 0.51$

$B_1 = 0.139 - \frac{0.172}{T__{\gamma}}^{ \ 4.2}}$

$B_1 = -0.282$

The compressibility is calculated as:

$Z = 1+ (B_o + \omega B_1 ) \frac{P__{\gamma}}{T__{\gamma}}$

$Z = 1+ (-0.51 +(0.345* - 0.282) ) \frac{0.0816}{0.808}$

Z = 0.9386

$V= \frac{ZRT}{P}$

$V= \frac{0.9386*8.314*10^3*523.15}{1800}$

V = 2268.01 cm³ mol⁻¹

c) From the steam tables (App. E).

At $T_1 = 523.15 \ K \ and \ P = 1800 \ k Pa$

V = 0.1249 m³/ kg

M (molecular weight) = 18.015 gm/mol

V = 0.1249 × 10³ × 18.015

V = 2250.07 cm³/mol⁻¹

R = 729.77 J/kg.K

Z = $\frac{PV}{RT}$

Z = $\frac{1800*10^3 *0.1249}{729.77*523.15}$

Z = 0.588

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3 years ago

Which describes an example of genetic engineering?

Marizza181 [45]

i think its number 3

4 0

3 years ago

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Which trait is most likely a result of artificial selection

ycow [4]

Answer:

Explanation:Artificial selection is distinct from natural selection in that it describes selection applied by humans in order to produce genetic change. When artificial selection is imposed, the trait or traits being selected are known, whereas with natural selection they have to be inferred. In most circumstances and unless otherwise qualified, directional selection is applied, i.e., only high-scoring individuals are favored for a quantitative trait. Artificial selection is the basic method of genetic improvement programs for crop plants or livestock (see Selective Breeding). It is also used as a tool in the laboratory to investigate the genetic properties of a trait in a species or population, for example, the magnitude of genetic variance or heritability, the possible duration of and limits to selection, and the correlations among traits, including with fitness.

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3 years ago