Answer:
Accuracy of a measured value refers to how close a measurement is to the correct value. The uncertainty in a measurement is an estimate of the amount by which the measurement result may differ from this value. Precision of measured values refers to how close the agreement is between repeated measurements.
Explanation:
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An unknown substance has a boiling point (oC) 20.0. Predict if the substance will be a Gas, Solid or liquid at the room temperature (25oC)?
Question 14 options:
Liquid
Gas
Solid
None of the above
How to figure out if equations are balanced chemistry.
Answer:
If each side of the equation has the same number of atoms of a given element, that element is balanced. If all elements are balanced, the equation is balanced.
What do all atoms in a period (horizontal rows) have in common?
Answer:
the same number of atomic orbitals.
Explanation:
Answer:
All of the elements in a period have the same number of atomic orbitals. For example, every element in the top row (the first period) has one orbital for its electrons. All of the elements in the second row (the second period) have two orbitals for their electrons.
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4. If the speed of an object increases, its kinetic energy
stays the same
decreases
increases
Answer:
I think the answer is increases
Refer to the following balanced equation in which ammonia
reacts with nitrogen monoxide to produce nitrogen and
water.
4NH3(g) + 6NO(g) → 5N2(8) + 6H2O(l)
How many moles of NO are required to completely react with
2.45 mol NH3 ?
4NH₃(g) + 6NO(g) → 5N₂(8) + 6H₂O(l)
The mole ratio of NO to NH₃ based on the balanced equation is 6 to 4 (or 3 to 2 in the simplest form)
Therefore in the reaction, there are ³/₂ more moles of NO than NH₃.
⇒ since moles of NH₃ = 2.45 mol
then moles of NO = 2.45 mol × ³/₂
= 3.675 mol
2.8 dm3 of gas X at STP has equal mass with 11.2 dm3 of C2H6 at STP. What is
the number of mole if gas X has 30 grams?
Answer: o.125 moles of gas X with a molar mass of 240
Explanation:
2.8 dm3 of gas X at STP has equal mass with 11.2 dm3 of C2H6 at STP. What is the number of mole if gas X has 30 grams?
the molar volume of any gas at STP is the volume of 1 mole at STP
and is 22.4 L
the C2H6 has a volume of 11.2L at STP so it has 0.5 moles
C2H6 has a molar mass of (2 X 12) +(6 X 1) = 24 + 6 = 30
0,5 moles weighs 15 gm at STP with
so 15 gm at STP with 2.8 L for gas X
PV=nRT
P=1 atm
T =273.2k
V =2.8
R =0.082
n = PV/RT = (1 X 2.8)/(0.082 X 273.2) =0.125 moles of gasX
the weight of gas X is 30 gms
so 30/.125 =240 g/mole = molar mass of gas X
How many moles are present in 1.39 grams of carbon?
C
R. F. M (Relative Formula Mass) of C=12
12g of C=1 mole
1.39g of C=(1*1.39)/12
=0.1158 moles
Write the configuration for electron: 4, 2, -1, +12
Answer:
-1
Explanation:
electrons are negative
How many cl- ions are there in 2. 50 kg of barium chooride.
The branch of chemistry that deals with the interconversion of electrical and chemical energy is called .
Answer:
Electrochemistry
Explanation:
33. Which element in Period 5 of the Periodic Table
is a transition element?
A) Sr
B) Ag C) Sb
D) Xe
Silver or Ag is the transition element present in period 5 of the periodic table.
What is periodic table?
Periodic table is a tabular arrangement of elements in the form of a table. In the periodic table, elements are arranged according to the modern periodic law which states that the properties of elements are a periodic function of their atomic numbers.
It is called as periodic because properties repeat after regular intervals of atomic numbers . It is a tabular arrangement consisting of seven horizontal rows called periods and eighteen vertical columns called groups.
Elements present in the same group have same number of valence electrons and hence have similar properties while elements present in the same period show gradual variation in properties due to addition of one electron for each successive element in a period.
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renal calculi contain crystallized calcium, magnesium, and uric acid. explain why patients with hyperparathyroidism would be at risk for developing renal calculi.
Patients with hyperparathyroidism would be at risk for developing renal calculi because of high calcium levels excreted by the kidney.
Hyperparathyroidism occurs when there is over secretion of parathyroid hormone by the parathyroid glands.
The parathyroid hormone is responsible for the following in the body:
Release of calcium by bones into the bloodstream. Absorption of calcium from food by the intestines, and Conservation of calcium by the kidneys.Renal calculi are strong masses of stones deposited in the kidneys or urinary bladder.
When there is excess calcium in the blood due to hyperparathyroidism, the kidneys would be over burdened with the excretion of excess calcium.
That extra calcium in the kidney & the urine leads to kidney stone development ( renal calculi).
Therefore, patients with hyperparathyroidism would be at risk for developing renal calculi because of high calcium levels excreted by the kidney.
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How do plants slow down erosion?
They slow down water as it runs downhill.
They speed up water as it runs downhill.
Their roots crack open rocks.
Their roots create new rock.
Answer:
I'm thinking the answer is gonna be it slows it down as it runs down hill
- A beam of electrons has.....
(A) Wave properties.
(B) Particle properties.
(C) Both of these
(D) Neither of these
Answer:
(C) Both of these
Explanation:
A beam of electrons has both of these Wave properties and Particle properties.
Which of the following is NOT a chemical reaction?
Select one:
a.
Hydrogen and oxygen combine to make water
b.
Ammonia breaks up into nitrogen and hydrogen
c.
Ice melts to form water
does apple pie need to be stored in the refrigerator?
Answer:
yes/no
Explanation:
I prefere it refrigerated because it lasts longer in my opinion. but some people keep it out
Answer:
yes.
Explanation:
It does unless you want warm soggy pie.
1. Determine how many atoms are present in 2.5 moles of Silicon? (15.05 x 1023 atoms)
X
To solve this, we have to turn the moles into atoms:
2.5 moles/1 x 6.022x10^23 atoms/1 mole = 15.05 x 10^23 atoms
Answer: 15.05 x 10^23 atoms
I hope this helps!
Silicon is the eighth most abundant element in the Universe. There will be 15.05 * 10²³ atoms in the silicon.
What is number of moles?Silicon is the eighth most abundant element in the Universe; it is made in stars with a mass of eight or more Earth suns.
Near the end of their lives these stars enter the carbon burning phase, adding helium nuclei to carbon to produce oxygen, neon, magnesium and silicon.
1 mole contains 6.022x10²³ atoms.
2.5 mole contains = x atoms.
x= 2.5 moles/ 6.022x10²³ atoms.
= 15.05 x 10²³ atoms
Therefore, Silicon is the eighth most abundant element in the Universe. There will be 15.05 * 10²³ atoms in the silicon.
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what is the difference in chemical energy between organic and inorganic materials?
Answer:
the difference is the presence of a carbon atom
Explanation:
4.16 Unit Test: Chemical Bonding - Part 2 1. You are studying alkaline earth metals bonding with Halogens. Using your knowledge of the ionic bonding, what specific and testable scientific question could be asked about the salt formation
A testable scientific question could be asked about the salt formation is; "Is the salt soluble in water?
A scientific question is a question that can be answered by experiments. In other words, a scientific question must be empirical. Its answer can only be obtained by carrying out experiments.
In the case of bonding in alkaline earth metals, the kind of bond formed is ionic. Ionic compounds are soluble in water. Hence, a testable scientific question could be asked about the salt formation is; "Is the salt soluble in water?
This can be answered by dissolving several salts of alkali earth metals in water.
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What part of the digestive tract that the food is broken into very small pieces?
mix the food with digestive juices that have acids and enzymes, breaking it into much smaller, digestible pieces
hope it helpsNaCl express your answer as an Ion
Does anyone know what the answer for this would be
Answer:
iconic compound
Explanation:
Which of the following describes how photochemical smog is bad for the environment?
1. Decreases crop yields
II. Interferes with amount of sunlight reaching plants
III. Mixes with moisture and becomes acidic
OI and 11
Oll and III
O I and III
O I, II, and III
Answer:
Its l and ll
Explanation:
it doesn't mix with moisture that would be sulfurous smog
Answer: 1 and 3
qwq rawr
Write the symbol for the atom with 38 protons, 36 electrons, and 50 neutrons and identify the element.
Answer:
Symbol: Sr2+
Element: Strontium
Explanation:
Strontium will have 38 protons, 38 electrons, and the neutron will depend on the isotope but there will usually be 48, 49, or 50 neutrons
Hope this Helps
Q.2. Which of the following statements is true of second ionization energies?
a) That of Al is higher than that of Mg because Mg wants to lose the second electron, so it is easier to take the second electron away
b) That of Al is higher than that of Mg because the electrons are taken from the same energy level, but the Al atom has one more proton
c) That of Al is lower than that of Mg because Mg wants to lose the second electron, so the energy change is greater
d) That of Al is lower than that of Mg because the second electron taken from Al is in a p orbital, so it is easier to remove it.
Answer:
a) That of Al is higher than that of Mg because Mg wants to lose the second electron, so it is easier to take the second electron away
Statement which is true regarding second ionization energy is that ionization energy of of Al is higher than that of Mg because Mg wants to lose the second electron, so it is easier to take the second electron away.
What is ionization energy?Ionization energy is defined as the minimum amount of energy required to remove an electron which is loosely held in the outermost shell to form an isolated gaseous atom,ion or molecule.
It has a positive value for neutral atoms indicating that the ionization process is an endothermic process . The closer the outermost shell electrons are to the nucleus of an atom higher is it's ionization energy.It is expressed in electron volts or joules.
Ionization energy increases across period as more energy is required to remove electron from an atom as it is closely held along a period while it is decreasing down the group as on going the group the inter-nuclear distance increases and as a result less energy is required to remove an electron.
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How do you find the frequency of a recorder?
Answer:
Modern recorders are most commonly pitched at A=440 Hz, but among serious amateurs and professionals, other pitch standards are often found. For the performance of baroque music, A=415 Hz is the de facto standard, while pre-Baroque music is often performed at A=440 Hz or A=466 Hz.
Explanation:
determine the element of lowest atomic number that contains a complete d subshell in the ground state.
Answer:
The element with the lowest atomic number that contains a complete d-subshell in the ground state is copper.Source:
Determine the element of lowest atomic number that contains a complete d subshell in the ground... - Study.comWhat physical change happens to atoms and molecules in a solution that is strongly heated in a flame? Is there a phase change? If so, what is it?
When atoms and molecules speed up or slow down, that is a physical change. When they change state from liquid to solid or from gas to liquid, that is a physical change. ... The ions or molecules can still come back together to form the original substance
The physical change which happens to atoms and molecules in a solution that is strongly heated in a flame is;
The atoms and molecules gain energy and their internal energy is increased.If the heat energy is sufficient, there is a phase change and this phase change is from liquid to gas (evaporation).Heating and Phase changesAtoms and molecules which are units of matter when strongly heated in a flame have increased internal energy and would undergo a phase change to a more energetic state of matter which is the gaseous state.
As such, the physical change that occurs in them is. increased internal energy.
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explain why boiling is a reversible change
Answer:
This is a reversible change. Similarly, if you boil water, it evaporates and becomes water vapor. When you cool this vapor down, it turns back to water. A change which cannot happen backward, that is, it cannot be reversed is called an irreversible change.
Explanation:
When we boil water by heating, then it changes into steam. Now, if we cool the steam, then water is formed again. So, the changing of water into steam has been reversed by cooling. Thus, the boiling of water (or evaporation of water) is a reversible change.
If pOH of the compound equals to 2, it shows that compound is *
Strong basic
Strong acidic
Weak acidic
Weak basic
what is the coefficient for 4K2CO3
