. Which one is NOT an INDICATOR that a chemical has occurred
A) Gas is produced
B) Precipitate is produced
C) Change in energy
D) Change in mass

Answer:  Formula: Mass = (Volume)(Density)

Iron Density = 7.87 g/cm^3

Volume of Iron = 55.2 cm^3

Mass=(V)(D)

Mass= (55.2 cm^3) x (7.87 g/cm^3)

Mass=  434,42 g

Explanation:

Iron has a density of 7.87 g/cm³. 434,42 g is the mass of 55.2 cm³ of iron.

The term density is defined as the measurement of how closely a material is packed together.

It is also defined as the mass per unit volume. Density Symbol is D or ρ Density Formula is ρ = m/V, where ρ is the density, m is the mass of the object and V is the volume of the object.

Density is an important because it allows us to find out what substances will float and what substances will sink when placed in a liquid.

Formula:

Mass = (Volume)(Density)

Given:

Iron Density = 7.87 g/cm³

Volume of Iron = 55.2 cm³

Mass=(V)(D)

Mass= (55.2 cm³) x (7.87 g/cm³)

Mass= 434,42 g

Thus, Iron has a density of 7.87 g/cm³. 434,42 g is the mass of 55.2 cm³ of iron.

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Answer:

175.5

Explanation:

Answer: See explanation

Explanation:

Digital technologies refers to the electronic tools, or devices that can be used to generate data, store them or process data. e.g. mobile phones, ebooks etc.

Digital learning makes use of technology. Effective use of digital learning tools can help increase the engagement of students. This csn.aksi be used by the teachers to enhance personalized learning and also improve the lesson plans.

Digital technology can enhance collaboration, and communication with the students. The use of videos, robots, virtual classrooms, augmented reality and other technologies can bring about fun and foster inquisitiveness.

Answer:

1.34 mol

Explanation:

Molarity, which is the molar concentration of a solution, can be calculated by dividing the number of moles (n) by the volume (V).

That is;

Molarity (M) = n/V

According to the information provided in this question;

M = 2.40M

V = 56.0 mL = 56/1000 = 0.056 L

Since molarity = n/V

number of moles = M × V

n = 0.056 × 24

n = 1.34 mol

Answer:

The benefits of Fluoride are rebuild (remineralize) weakened tooth enamel.slow down the loss of minerals from tooth enamel.reverse early signs of tooth decay.prevent the growth of harmful oral bacteria

Answer:

Fluoride is often called nature's cavity fighter and for good reason. Fluoride, a naturally-occurring mineral, helps prevent cavities in children and adults by making the outer surface of your teeth (enamel) more resistant to the acid attacks that cause tooth decay.

Answer: [tex]2NH_3(g)+2O_2(g)\rightarrow N_2O(g)+3H_2O(l)+684kJ[/tex]

Explanation:

The skeletal thermochemical equation for the reaction is:

[tex]NH_3(g)+O_2(g)\rightarrow N_2O(g)+H_2O(l)+342kJ[/tex]

The balanced  thermochemical equation for the reaction is:

[tex]2NH_3(g)+2O_2(g)\rightarrow N_2O(g)+3H_2O(l)+684kJ[/tex]

When 1 mole of [tex]NH_3[/tex] reacts with oxygen , heat released = 342 kJ

Thus when 2 moles of [tex]NH_3[/tex] reacts with oxygen , heat released = [tex]\frac{2}{1}\times 342 kJ=684kJ[/tex]

Answer: Q = mlvap

Q = (2 kg)(1 kmol/197 kg)(1,000 mol/1 kmol)

Q = 10.15 kJ

2126  joules of energy in form of thermal energy  is required to vaporize 2 kg of gold.

Thermal energy is defined as a type of energy which is contained within a system which is responsible for temperature rise.Heat is a type of thermal energy.It is concerned with the first law of thermodynamics.

Thermal energy arises from friction and drag.It includes the internal energy or enthalpy of a body of matter and radiation.It is related to internal energy and heat .It arises when a substance whose molecules or atoms are vibrating faster.

These vibrating molecules and atoms collide and as a result of which heat is generated in a substance , more the collision of particles , higher is the thermal energy.

Amount of heat is calculated as, Q=2×1063 =2126 joules as per the given formula.

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Answer:

4.48 L O2

Explanation:

At STP, a mole of any gas contains 22.4 liters. Therefore, we simply have to multiply the amount of moles by 22.4

0.2mol O2 ( 22.4 L) = 4.48 L O2

Answer:

0.54 L

Explanation:

Given that,

Initial volume, V₁ = 0.5 L

Initial temperature, T₁ = 10°C = 283 K

Final temperature, T₂ = 35 C = 308 K

We need to find the final volume. The relation between the volume and temperature is given by :

[tex]\dfrac{V_1}{T_1}=\dfrac{V_2}{T_2}\\\\V_2=\dfrac{V_1T_2}{T_1}\\\\V_2=\dfrac{0.5\times 308 }{283}\\\\V_2=0.54\ L[/tex]

So, the new volume is 0.54 L.

Answer:

We can simply refer to the cation in the ionic compound as magnesium. Phosphorus, Pstart text, P, end text, is a group 15 element and therefore forms 3- anions.

Explanation:

Because it is an anion, we add the suffix -ide to its name to get phosphide as the name of the ion.

Answer:

The weak acid is - E. [tex]NH_3[/tex]

Explanation:

Ammonia is a strong base, which in turn make it to be a weak acid.

As, the rest of the options are acid and therefore furnish hydrogen ions when dissolved in water, making them strong acid.

And ammonia dissolves in water to form its conjugate ammonium ion and hydroxide ion, therefore making the solution basic.

Hence, from the given options, the correct option is E. [tex]NH_3[/tex]

The compound which when dissolved in water, forms a weak acid is; Choice E: NH3

According to the question;

Unlike other compounds (HNO3, HClO, HBr, HClO) which dissolve in water to yield H+ ion, Ammonia dissolves in water to form ammonium ion and hydroxide ion, OH-.

In essence, NH3 is a strong base when dissolved in water and consequently, is a weak acid when dissolved in water.

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Answer:

they can track the weather which can show if it would be posssible to live or have life on mars

Explanation:

Answer: pH of buffer solution is 8.1

Explanation:

The formula for the Henderson–Hasselbalch equation is:

[tex]pH=pK_a+\log\frac{[A^-]}{[HA]}[/tex]

[tex]pH[/tex] is the concentration of [tex][H^+][/tex]

[tex]pK_a[/tex] is the acid dissociation constant,

[tex]A^-[/tex] and [tex]HA[/tex] are concentrations of the conjugate base and starting acid.

Putting in the values we get:

[tex]pH=7.5+\log\frac{x}{\frac{x}{4}}[/tex]

[tex]pH=8.1[/tex]

Thus pH of buffer solution is 8.1

Answer:

[tex]V_{7.0}\approx 235ml[/tex]

Explanation:

From the question we are told that

mass of sample [tex]M=72.0 grams[/tex]

volume of water [tex]V=180 mL[/tex]

volume for extraction [tex]V'=60mL[/tex]

partition (distribution) coefficient water [tex]d=10[/tex]

initial extraction removal [tex]x=55.4g[/tex]

Generally the equation for the weight of sample [tex]x_n[/tex]  is mathematically given by

[tex]x_n=x*(\frac{DV}{DV+V'})^n[/tex]

[tex]x_n=55.4(\frac{10*180}{10*180+60})^1[/tex]

[tex]x_n=53.613g[/tex]

Generally the weight extracted [tex]x_e[/tex] is therefore

[tex]w_e=x-x_n[/tex]

[tex]w_e=55.4-53613[/tex]

[tex]w_e=1.787[/tex]

[tex]w_e=1.787[/tex] is extracted with 60ml solvent .

Therefore volume of solvent (y) that would be necessary to remove an additional 7.0g

[tex]V_{7.0}=\frac{60}{1.767}*7[/tex]

[tex]V_{7.0}=235.030ml[/tex]

[tex]V_{7.0}\approx 235ml[/tex]

Answer:

Dominant

Explanation:

hope this help

Answer:

As of right now (4-7-2021), the physical science requirement for the SLP certificate must be met by completing coursework in the areas of either chemistry or physics.

Answer:

helium is the answer

Explanation:

helium is the smallest element in francium is the largest hope this helps

Answer: The discovery of three buried lakes. Scientists think that a long time ago there were lakes and rivers, etc on Mars. Now of course, you can't see any visible water sources on the surface.

Answer:

Almost all water on Mars today exists as ice, though it also exists in small quantities as vapor in the atmosphere.[5] What was thought to be low-volume liquid brines in shallow Martian soil, also called recurrent slope lineae may be grains of flowing sand and dust slipping downhill to make dark streaks.The only place where water ice is visible at the surface is at the north polar ice cap. Abundant water ice is also present beneath the permanent carbon dioxide ice cap at the Martian south pole and in the shallow subsurface at more temperate conditions. More than 5 million km3 of ice have been detected at or near the surface of Mars, enough to cover the whole planet to a depth of 35 meters. Even more ice is likely to be locked away in the deep subsurface.

Some liquid water may occur transiently on the Martian surface today, but limited to traces of dissolved moisture from the atmosphere and thin films, which are challenging environments for known life. No large standing bodies of liquid water exist on the planet's surface, because the atmospheric pressure there averages just 600 pascals , a figure slightly below the vapor pressure of water at its melting point; under average Martian conditions, pure water on the Martian surface would freeze or, if heated to above the melting point, would sublime to vapor. Before about 3.8 billion years ago, Mars may have had a denser atmosphere and higher surface temperatures, allowing vast amounts of liquid water on the surface, possibly including a large ocean that may have covered one-third of the planet.Water has also apparently flowed across the surface for short periods at various intervals more recently in Mars' history. Aeolis Palus in Gale Crater, explored by the Curiosity rover, is the geological remains of an ancient freshwater lake that could have been a hospitable environment for microbial life.Many lines of evidence indicate that water ice is abundant on Mars and it has played a significant role in the planet's geologic history.The present-day inventory of water on Mars can be estimated from spacecraft images, remote sensing techniques (spectroscopic measurements, radar, etc.), and surface investigations from landers and rovers.Geologic evidence of past water includes enormous outflow channels carved by floods, ancient river valley networks, deltas and lakebeds,and the detection of rocks and minerals on the surface that could only have formed in liquid water. Numerous geomorphic features suggest the presence of ground ice (permafrost)and the movement of ice in glaciers, both in the recent past and present. Gullies and slope lineae along cliffs and crater walls suggest that flowing water continues to shape the surface of Mars, although to a far lesser degree than in the ancient past.Although the surface of Mars was periodically wet and could have been hospitable to microbial life billions of years ago, the current environment at the surface is dry and subfreezing, probably presenting an insurmountable obstacle for living organisms. In addition, Mars lacks a thick atmosphere, ozone layer, and magnetic field, allowing solar and cosmic radiation to strike the surface unimpeded. The damaging effects of ionizing radiation on cellular structure is another one of the prime limiting factors on the survival of life on the surface. Therefore, the best potential locations for discovering life on Mars may be in subsurface environments. Large amounts of underground ice have been found on Mars; the volume of water detected is equivalent to the volume of water in Lake Superior. In 2018, scientists reported the discovery of a subglacial lake on Mars, 1.5 km (0.93 mi) below the southern polar ice cap, with a horizontal extent of about 20 km (12 mi), the first known stable body of liquid water on the planet.Understanding the extent and situation of water on Mars is vital to assess the planet’s potential for harboring life and for providing usable resources for future human exploration. For this reason, "Follow the Water" was the science theme of NASA's Mars Exploration Program (MEP) in the first decade of the 21st century. NASA and ESA missions including 2001 Mars Odyssey, Mars Express, Mars Exploration Rovers (MERs), Mars Reconnaissance Orbiter (MRO), and Mars Phoenix lander have provided information about water's abundance and distribution on Mars.Mars Odyssey, Mars Express, MRO, and Mars Science Lander Curiosity rover are still operating, and discoveries continue to be made.

Answer:

Cr 6+ & SO4 2-

Explanation:

Sulfate is a polyatomic ion that has a charge of 2-. There are three of them in the chemical formula so it equates to a 6- total charge. Thus, chromium must have a 6+ charge to give the compound a neutral charge.

Explanation:

by dissolving the mixture of lead sulphate and lead chloride in water we can separate the two. after dissolving the mixture on water lead sulphate can be obtained as the solid that 's left behind lead chloride can be recovered by evaporating.

Answer:

coal

Explanation:

Answer: 1:7

Explanation: 2 Tc^+7 + 7 O2^-2 -> Tc2 (O2)7

Also 2 Tc to 14 O

Answer:

27.27%

Explanation:

The longest continuous carbon chain comprises five carbon atoms connected by single bonds, so the root name will be pentane. There is a methyl group (—CH3) attached to carbon 3 (since this molecule is symmetrical, the methyl substituent will always be on carbon 3 regardless of which end you begin counting). Thus, the name of this molecule would be 3-methylpentane.

Answer:

The correct answer is - 4-nitroaniline.

Explanation:

It is given that all three solid compounds salicylic acid + 4-nitroaniline + naphthalene are equal in the ratio in the mixture and then 1 gram of this mixture is dissolved in the diethyl ether and run a drop of the solution on TLC plate. This plate shows three spots.

The salicylic acid and naphthalene would stay dissolved in the diethyl ether solution due to the 4-nitroaniline could be extracted by adding aqueous acid and involve in the aqueous layer and thus spot of 4-nitroaniline would be with largest Rf value.

Answer:

The correct answer is -

a) Sodium acetate: least Ammonia: _______ Sodium ethoxide: most

b) Sodium acetate: most Sodium chloroacetate: _______ Sodium fluoroacetate: least

c)  Sodium acetate: least Sodium methoxide: most Sodium phenoxide:

Explanation:

A) In this case the basicity can be found by the stability of the base, Sodium acetate is the most stable base due to resonance stabilization of acetate anion. Sodium acetate is the least basic as the lone pair of electrons involved in the resonance here. An ethoxide ion has more electrons to donate an electron pair easily.

Thus, the correct answer is - Sodium acetate is the least basic while sodium ethoxide is the most basic.

B) Fluroacetate gives a very strong acid and the acetate gives the least strong acid among all three as described in case of a), thus, the most basic is acetate and the least is fluoroacetate.

]C) comparing the acidity of the acids formed by the addition of a proton to the anions is an easy and correct way to find the basicity of compounds.

Acetate ion adds a proton ⇒ acetic acid

methoxide adds a proton ⇒ methanol

phenoxide ion adds proton ⇒ phenol

As it is known that the stronger the acid, the weaker is the conjugate base formed by the loss of the proton.

acetic acid is the strongest acid because it can easily give up its proton to form acetate. Methanol is the weakest among all three and hence methoxide anion is the strongest base.

Thus, the correct answer is - sodium acetate is the least basic while sodium methoxide is the most basic.

The volume of the balloon is 2.1L.

Volume is the amount of space the matter occupies. The SI unit of volume is cubic meter.

Using Boyles law equation,

P1V1 = P2V2

Where P1 and V1 are the initial pressure and volume of the gas

           P2 and V2 are the final pressure and volume of the gas

Given:

P1 = 3.5atm

V1 = 4.2L

P2 = 7.0atm

V2 = ?

Solve for V2 ,

V2 = P1V1/P2

V2 = (3.5atm x 4.2 L) / (7.0atm)

     = 2.1L

Hence, the volume of the balloon is 2.1L.

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