Answer:
true or false
a. very little oxygen and nitrogen are found in air. false
b. oxygen is the main cause of the formation of rust in iron. false
c. impure air is odourless true
.d. plants take in oxygen gas during respiration. true
e. air contains water vapour. true
Explanation:
How many electrons does chlorine need to gain in order to be like Argon ?
- 2 electrons
- 3 electrons
- 1 electron
Which element on the periodic table is the lowest mass in period 4??
Answer:
potassium I believe is the correct answer
Explanation:
Potassium is the period four element with the lowest mass; its average mass is 39.0983amu.
The fourth period of the periodic table is where potassium has its lowest atomic mass.
What is atomic mass?Atomic mass is defined as the combined mass of an atom's protons, neutrons, and electrons. The term "atomic mass" refers to the weight of an atom or molecule. To determine the average mass of elements and molecules as well as to resolve stoichiometry issues, the atomic mass is used.
An electrically neutral atom has an equal number of protons and electrons. As a result, using any of the two formulas, we may calculate the atomic mass of an element. The atomic mass of an element grows as we move from left to right in a period of the periodic table. In the fourth period of the current periodic table, Krypton has the highest atomic mass and potassium has the lowest.
Thus, the fourth period of the periodic table is where potassium has its lowest atomic mass.
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why are electric switches and boards are made up of plastic
why are electric switches and boards are made up of plastic
Answer:-Because plastic is a poor conductor of electricity.
Explanation:-Plastics do not conduct enough heat and electricity. Therefore, it is used in the manufacture of plug switches, plug boards, etc.
Determine the number of moles in 4.9*10 raise to the power of 24 of Ag
Answer:
4.5425806678891E+22mol
Explanation:
The value of probability density will be
The probability density function is nonnegative everywhere, and its integral over the entire space is equal to the terms "probability distribution function" and "probability function" .
What is probability density function?
In probability theory, a probability density function (PDF), or density of a continuous random variable, is a function whose value at any given sample (or point) in the sample space (the set of possible values taken by the random variable) can be interpreted as providing a relative likelihood that the value of the random variable would be equal to that sample.
Probability density is the probability per unit length, in other words, while the absolute likelihood for a continuous random variable to take on any particular value is 0 (since there is an infinite set of possible values to begin with), the value of the PDF at two different samples can be used to infer, in any particular draw of the random variable, how much more likely it is that the random variable would be close to one sample compared to the other sample.
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the property of matter that determines whether or not an electrical current can pass through it
( picture ) identify each type of reaction shown below
it wouldnt let me type it because it said it was too inappropriate
Explanation:
the normal human eye responds to visible light of wavelength range from about 390 to 710nm. Determine the frequency range of the human eye.
Explanation:
=>7.7 x10¹⁴ to 4.2 x10¹⁴Hz
Which property is the same for a 50 mL sample of liquid water and a 100 mL sample of liquid water?
Answer: The density because it stays the same with any same liquids or solids or gas with whatever amount of it is added. It only changes if the matter of state is different or there is any environmental change.
What element makes up graphene
napthalene combustion can be used to calibrate the heat capacity of a bomb calorimeter The heat of combustion of naphthalene is -40.1kj/g. When .8210g of naphthalene was burned in a calorimeter containing 1,000g of water, a temperature rise of 4.21C was observed. What is the heat capacity?
A bomb calorimeter with a heat capacity of 3.63 kJ/°C experiences a temperature rise of 4.21 °C when .8210 g of naphthalene is burned.
The combustion of naphthalene is used to calibrate the heat capacity of a bomb calorimeter.
What is a bomb calorimeter?It is a device used to measure the change in the internal energy of a reaction.
To determine the heat capacity of the calorimeter (C), we need to follow a series of steps.
Step 1: Calculate the heat released by the combustion.The heat of combustion of naphthalene is -40.1kJ/g and .8210g were burned.
Qcomb = -40.1kJ/g × .8210g = -32.9 kJ
Step 2: Determine the heat absorbed by the bomb calorimeter.According to the law of conservation of energy, the sum of the heat released by the combustion and the heat absorbed by the bomb calorimeter is zero.
Qcomb + Qbomb = 0
Qbomb = -Qcomb = 32.9 kJ
Step 3: Calculate the heat capacity of the bomb calorimeter.32.9 kJ were absorbed, part by the calorimeter itself and part by the 1,000 g (m) of water, whose specific heat capacity (c) is 4.18 J/g°C.
A temperature rise (ΔT) of 4.21 °C is observed. We can determine the heat capacity of the bomb calorimeter (C) using the following expression.
Qbomb = Qcal + Qwater
32.9 kJ = C × ΔT + c × m × ΔT
32.9 kJ = C × 4.21 °C + (4.18 × 10⁻³ kJ/g.°C) × 1,000 g × 4.21 °C
C = 3.63 kJ/°C
A bomb calorimeter with a heat capacity of 3.63 kJ/°C experiences a temperature rise of 4.21 °C when .8210 g of naphthalene is burned.
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In an experiment, equal amounts of water and sand were heated under a lamp. The initial and final temperatures of each were recorded. A partial record of the temperature is shown.
Experimental RecordSubstance Initial Temperature Final Temperature
Sand 20 °C 26 °C
Water 20 °C ?
Which statement about the final temperature of water is correct?
A. It will be less than 26 °C as sand has a relatively higher specific heat than water.
B. It will be less than 26 °C as water has a relatively higher specific heat than sand.
C. It will be more than 26 °C as sand needs relatively higher energy than water to raise its temperature.
D. It will be more than 26 °C as water needs relatively higher energy than sand to raise its temperature.
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will be less than 26 °C as water has a relatively higher specific heat than sand.
Explanation:
The specific heat of a substance is the amount of heat energy absorbed by one unit of mass of the substance when its temperature increases one unit.
From that, you can derive the equation for the specific heat of a substance:
specific heat = heat / (mass × ΔT)
Thus, assuming that all the heat provided by the lamp to both samples is the same and, as given, the amount (mass) of both samples is also the same, you have that the specific heat of the samples will be:
specific heat = constant / ΔT
So, specific heat and ΔT are inversely related.
It is known that water has a higher specific heat than sand (that is why the sand on the shore of a beach is, during the day, hotter than the water and your feet get burned when you walk on a sandy beach on a sunny day
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Answer:
55 centimeters
Explanation:
20+15+25
Which list correctly compares how adding energy affects a substance during a phase change and not during a phase change?(1 point)
during a phase change: particles overcome forces of attraction and temperature stays the same
not during a phase change: particles become closer together
during a phase change: particles overcome forces of attraction and temperature stays the same
not during a phase change: temperature rises
during a phase change: particles overcome forces of attraction and temperature rises
not during a phase change: particles become closer together
during a phase change: particles overcome forces of attraction and temperature rises
not during a phase change: temperature rises
Which action happens at the microscopic scale as the temperature of a substance decreases and it eventually freezes?(1 point)
Particle motion decreases, and electrostatic forces pull particles closer together.
Particle motion increases, and the particles overcome electrostatic forces.
Particle motion decreases, and the particles overcome electrostatic forces.
Particle motion increases, and electrostatic forces pull particles closer together.
Which statement describes how a macroscopic property of gases provides information about microscopic gas particles?(1 point)
Gases fill their container, showing that gas particles are strongly attracted through electrostatic forces.
Gases have a fixed volume, showing that gas particles are strongly attracted through electrostatic forces.
Gases fill their container, showing that gas particles are not tied together and can move far apart.
Gases have a fixed volume, showing that gas particles are not tied together and can move far apart.
Answer:
1) during a phase change: particles overcome forces of attraction and temperature stays the same not during a phase change: temperature rises 2)Particle motion decreases, and electrostatic forces pull particles closer together.
3) Gases fill their container, showing that gas particles are not tied together and can move far apart.
Explanation:
A bottle rocket takes off with a speed of 13 m/s and is angled 55 degrees above the horizon. What is the Y component of the velocity ?
Answer:
10.53m/s
Explanation:
Initial velocity: 13m/s
Angle of projection: 55deg
Y-component of velocity is given as usin⌀
Plugging in, we get
= 13 * sin(55deg)
= 13 * 0.81
= 10.53
⇒ 10.53m/s
Write the IUPAC names for the following compounds.
Pls help!
Describe ionic and covalent bonding.
Give an example of each
Answer:
Example of ionic bonds— Sodium chloride and calcium oxide. Example of covalent bond— Water, carbon
Explanation:
ionic bond, also called electrovalent bond, type of linkage formed from the electrostatic attraction between oppositely charged ions in a chemical compound. Such a bond forms when the valence (outermost) electrons of one atom are transferred permanently to another atom.
A covalent bond consists of the mutual sharing of one or more pairs of electrons between two atoms. These electrons are simultaneously attracted by the two atomic nuclei. A covalent bond forms when the difference between the electronegativities of two atoms is too small for an electron transfer to occur to form ions.
Explain the verse below in your own words in a little summary.
Hebrews 11:7
God had warned Noah of the flood and directed him to build an ark. Noah had faith in God and began building.
Answer:
God Warned Noah for the Flood comindg to Earth to wash away all the bad people's lives and god also said get couple animals girls and boys then build an ark then bring your family and food there to then noah had a faith in god so he obey and start builind the ark in a top of a mountain
Explanation:
Hebrews 11:7
Which of these is a characteristic of warm air?
It transfers energy through radiation.
Its molecules are far apart.
It sinks due to convection.
It cools the land below it.
Answer: B.
Explanation:
Warm air molecules are far apart, while cool air molecules are packed closer together.
Answer: A It Transfers energy through radiation
Explanation: I jut got done with the exam 15 min ago
How many moles does 205 g of helium,He, contain ?
Answer:
4.002602
Explanation:
Seems Am Converting Between Grams Helium And Mole.
Which of the following could be classified as unleavened bread?
sourdough bread
muffins
tortilla
bagels
Answer:
Tortilla
Explanation:
Answer:
tortilla
Explanation:
1) Convert the following:
900g to kg
2.87L to uL
Answer:
0.9 kg
2870000 uL
there is a conversion calculator online
Which are the two key factors that affect the rate of weathering of rocks?
Select 2.
A Climate
B Rock Type
C Bedrock
Answer:
A and B.
Explanation:
Climate:
High temperatures and greater rainfall increase the rate of chemical weathering. Lower temperatures can break rocks to by freezing water inside of a rock cracks. When it freezes it expands the water and forces the crack of the rock to expand.
Rock Type:
Certain types of rock are very resistant to weathering. Igneous rocks, especially intrusive igneous rocks such as granite, weather slowly because it is hard for water to penetrate them. Other types of rock, such as limestone, are easily weathered because they dissolve in weak acids.
calculate the number of molecules in 4.48dm3 of hydrogen at STP
Answer: 1 more of hydrogen =22.4dm3
X moles of hydrogen =4.48dm3
22.4dm3x = 4.48dm3
4.48dm3\22.4dm3
X=0.2 moles
Explanation: 1 volume of hydrogen at STP is 22.4dm3
Why must labs that use mercury thermometers calculate Kelvin ?
Answer:
because those are the only thermometers that are truly accurate for kelvins
Explanation:
The Kelvin temperature in thermometers is used by scientists because it provides a temperature where zero indicates the complete absence of thermal energy.
What is the Kelvin scale?All thermometers have a scale on them that we use to find the temperature, known as a temperature scale. Kelvin proposed that the temperature interval from the ice point to the steam point be defined as 100° containing earlier centigrade scales.
Lord Kelvin had given an absolute temperature scale based on the Carnot cycle. The zero point is 273.15 on Kelvin’s scale below that of the Celsius scale.
On the kelvin scale, Each division is called a Kelvin (K) and is equal to a degree on the Celsius scale. On the Celsius scale, zero degrees is the freezing point of water while on the Kelvin scale the zero point is at absolute zero temperature.
Therefore, 0 K is equal to - 273.15°C, and 0°C is equal to 273.15 kelvins. A mathematical expression that gives the relation between the Celsius and Kelvin scales:
Temperature (K) = Temperature (°C) + 273
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Which layer of the atmosphere reflects radio waves back to Earth?
A. Mesosphere
B. Stratosphere
C. Thermosphere
D. Troposphere
Answer:
Thermosphere
Explanation:
More specifically the ionosphere, since the ionosphere is the lower part of the thermosphere.
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PLEASE HELP ME!!
The molar mass of BF3 is 67.81 g/mol. How many molecules of BF3 are there in 2 g? (1 point)
A) 1.776 x 1022
B) 8.881 x 1021
C) 1.204 x 1024
D) 4.084 x 1025
Answer:
A
Explanation:
We are given that the molar mass of boron triflouride BF₃ is 67.81 g/mol. We want to determine the number of molecules of BF₃ in 2 g of BF₃.
Recall that there are 6.02 × 10²³ molecules in any mole of a substance. In other words, there are 6.02 × 10²³ BF₃ molecules in a mole of BF₃. Starting with the initial value, multiply:
[tex]\displaystyle \begin{aligned} 2\text{ g BF$_3$}&\cdot \frac{1\text{ mol BF$_3$}}{67.81 \text{ g BF$_3$}} \cdot \frac{6.02\times 10^{23} \text{ molecules BF$_3$}}{1 \text{ mol BF$_3$}} \\ \\ &= 1.776 \times 10^{22} \text{ molecules BF$_3$}\end{aligned}[/tex]
Hence, our answer is A.
*Perhaps it rendered the values incorrectly, but since we started with only 2 g of BF₃, our resulting calculation should only contain one significant digit. Hence, the correct answer should be 2 × 10²² molecules of BF₃.
The molecules of BF₃ that are there in 2 g is 1.776 × 10²² molecules and the correct option is option A.
The mole is an amount unit similar to familiar units like pair, dozen, gross, etc. It provides a specific measure of the number of atoms or molecules in a bulk sample of matter.
A mole is defined as the amount of substance containing the same number of atoms, molecules, ions, etc. as the number of atoms in a sample of pure 12C weighing exactly 12 g.
Given,
Molar mass of BF₃ = 67.81 g/mol
Mass = 2g
Moles = mass / molar mass
= 2 / 67.81
= 0.029 moles
1 mole = 6.023 × 10²³
0.029 moles = 6.023 × 10²³ × 0.029
= 1.776 × 10²² molecules
Thus, the ideal selection is option A.
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What equipment is generally used to make lyophilized medications suitable for administering to the patient? a) Test tubes or sterile ampules b) Petri dishes and sterile droppers c) Sterile syringes or graduated cylinders d) Measuring cups and clean, warm water
The answer is (B) !
Explanation:
Petri dishes and sterile droppers is generally used to make lyophilized medications suitable for administering to the patient.
- 5. Venus is like Earth because A. They both have oceans, air, and plant life. B. They both have people living on them. C. They are about the same size and have about the same amount of gravity.
Answer:
C
Explanation:
Answer:
c
Explanation:
Venus and Earth are often called twins because they are similar in size, mass, density, composition and gravity. Venus is actually only a little bit smaller than our home planet, with a mass about 80% of Earth's.
Check the box under each molecule in the table below that is an isomer of this molecule:
The branched alkanes in boxes two and three all have molecular formula C6H14 and are isomers of the compound shown.
Isomers are compounds that has the same molecular formula but different structural formulas. Hence, isomers of compounds can be represented by the same molecular formula since they contain the same number of each atom.
The molecule shown has molecular formula C6H14. The branched alkanes in boxes two and three all have molecular formula C6H14 and are isomers of the compound shown.
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