Which of the following elements will have its valence electrons represented as in Figure A?
I. Oxygen and Sulfer
II. Selenium and Tellurium
III. Polonium only
A. I only
B. II only
C. III only
D. I, II, and III
Which is a disadvantage of using chemical indicators?
They are expensive to use.
They measure pH directly.
They must be selected for a narrow pH range.
They do not use electricity to operate.
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Answer:
They must be selected for a narrow pH range.
Explanation:
Indicators are compounds that change to a specific colour in a solution within a specific pH range.
The chemical indicators does not give the exact value of pH. They only provide the range of pH. They must be selected for a narrow pH range. The correct option is C.
What is chemical indicator?The acid base indicators or neutralization indicators are substances which are employed for the visual detection of the end point on the basis of their ability to change colour during the pH change that occurs in vicinity of the end point.
The chemical indicators are usually weak organic acids or bases which change colour in characteristic pH ranges. The particular range or interval of pH in which an acid-base indicator changes its colour is known as the colour-change interval.
Methyl orange is a weak base which changes its colour in the pH range 3.1-4.4 being red below pH 3.1 and yellow above pH 4.4.
Thus the correct option is C.
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Growing the same crop on the same field year after year
A)
enriches the soil content.
B)
promotes a higher plant yield.
C)
raises the risk of increasing the number of pests in that area.
D)
guarantees that the plants will intake all the fertilizers applied.
Answer: The answer is D,
For each of the following questions give the name of an element from period 2 lithium to neon which matches the description elements may be used once more than once or not at all
a) an element which has atoms with a full outer shell of electrons
b) an element which exists as both diamond and graphite
c) an element that reacts vigorously with cold water
d) a soft metallic element which is stored in oil
PLEASEEE
The elements of period 2 that satisfy the descriptions are;
a) Neon
b) carbon
c) sodium
c) sodium
What is the periodic table?We know that the periodic table is an arrangement of the elements in the order of their reactivity. We know that the elements that we have are arranged into groups and periods.
The elements that are in the same group do have similar chemical properties while the elements that are in the same period do have the same number of shells. The properties of the elements in a periods tends to change across the period.
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A student titrated 60 mL of 0.2 M HCl solution
with 15 mL of Mg(OH)2 solution. What is the
concentration of the base solution?
Answer:
The concentration is 0.2 M HCI / 15mL 62g
Explanation:
----->
Use your knowledge of atoms, bonding, and the periodic table to complete the chemical equation .”CH4 + O2
and predict the products of the chemical reaction on your paper. Label this equation “Initial Prediction.
Answer:
CH4 + O2 = CO2 + H2O.
Answer:
CH4 + O2 = CO2 + H2O.
Explanation:
1. A wave has a frequency of 800 Hz and a wavelength of 2000 cm. What speed
is this wave traveling?
Answer:
V=f*(wavelength)
V= (800)(20m)
16000m/s
Explanation:
does lithium violate the octect rule
Answer: Lithium, an alkali metal with three electrons, is also an exception to the octet rule. Lithium tends to lose one electron to take on the electron configuration of the nearest noble gas, helium, leaving it with two valence electrons. There are two ways in which atoms can satisfy the octet rules.
Explanation: Hope this helped! :)
If you're wearing a yellow shirt in magenta light, what colour does the shirt look like now?
When using a flame to heat a liquid in a test tube, which one is NOTsafe
A.
the test tube is open (no rubber stopper)
B.
the open end is pointed away from you and your lab partner
C.
the test tube is closed with a rubber stopper
D.
the hot tube must be cooled before placing it into an ice bucket
Answer:
A ( I think? )
Explanation:
your welcome
What is the molarity of 6.2 moles of NaCl in 2.5 L of water?
Full work plz
Molarity= no. of moles of solute/ volume of solution(in L)
Molarity = 6.2 moles/ 2.5 L = 62/25 mol/L
= 2.48 mol/L
How many grams of lithium are in 3.50 moles of lithium
Identify the type of wave that would be located at Point A below.
1 mole of any gas is equivalent to?
Answer:
22.4 L at standard temperature and pressure.
How much energy is released when 67.04g of phosphorous is reacted with 10.20g of chlorine? ___ P + ___ Cl2 ___ PCl3 ΔH = -574 kJ
Answer:
26.78 kJ
Explanation:
To solve the problem, we have to first write the stoichiometric coefficients in the chemical equation:
2P + 3Cl₂ → 2PCl₃
With these coefficients, we have the same number of atoms of each chemical element on both sides: 2 atoms of P, 6 atoms of Cl.
According to the equation, 2 moles of phosphorous (P) react with 3 moles of chlorine (Cl₂), and 574 kJ of energy are released. We have to figure out which is the limiting reactant. For this, we convert the mass into moles by using the molar mass(MM):
MM(P) = 30.9 g/mol
67.04 g P/(30.9 g/mol) = 2.17 mol P
MM(Cl₂) = 35.4 g/mol x 2 = 70.8 g/mol
10.20 g Cl₂/(70.8 g/mol) = 0.14 mol Cl₂
Now, we multiply the actual moles of P (the amount we have for the reaction) by the stoichiometric ratio given by the chemical equation (3 mol Cl₂/2 mol P):
2.17 mol P x (3 mol Cl₂/2 mol P) = 3.25 mol Cl₂
To completely react 67.04 g P, we need 3.25 mol of Cl₂, and we have only 0.14 moles of Cl₂, so the limiting reactant is Cl₂.
Now, we use the limiting reactant to calculate the energy released from the reaction. The energy released per mole of Cl₂ is:
ΔH/(3 mol Cl₂) = -574 kJ/3 mol Cl₂= 191.3 kJ/mol Cl₂
Finally, we multiply the energy released per mole of Cl₂ by the number of moles of Cl₂ we have:
0.14 mol Cl₂ x 191.3 kJ/mol Cl₂ = 26.78 kJ
What is the application of separating funnel
Answer:
Used for liquid extractions
Explanation:
Answer:
the application of separating funnel is
to separate immiscible liquids from their solutes.
1. Using the structural formulas for ammonia (NH3 on the left) and hexane (C6H14 on the right) below which statement explains what will happen when ammonia and hexane are mixed?
A. Hexane will dissolve with ammonia if you stir them together for 10 minutes
B. Ammonia and hexane will not dissolve because one molecule is polar and the other is non polar.
C. Ammonia and hexane will dissolve together
D. Ammonia and hexane will not dissolve because one molecule is ionic and the other is non polar
2. If you add water to 750.0 mL of a 2.800 M KCl solution, and its molarity changes to 1.500 M, what will the new volume be?
1200 mL
401.0 mL
1400 mL
800.0 mL
Answer:
1. B. Ammonia and hexane will not dissolve because one molecule is polar and the other is non polar.
2. 1400 mL
Explanation:
In chemistry, like dissolve like! Ammonia is a polar molecule having a significant dipole moment owing to its three N-H bonds. On the other hand, hexane is a purely non-polar hydrocarbon hence the two substances can never dissolve in each other.
From the dilution formula;
C1V1=C2V2
C1= Initial concentration of the solution
V1 = Initial volume of the solution
C2 = Final concentration of the solution
V2= Final volume of the solution
2.8 M * 750.0 mL = 1.5 M * V2
V2 = 2.8 M * 750.0 mL/1.5 M
V2 = 1400 mL
weeks and how much money, in dollars, Jamal deposits into the savings account.
Week
Deposit (dollars)
0
10
1
15
2
20
3
25
4
30
Let f ()represent the amount of money Jamal deposits into his savings account at the end of 2 weeks. Based on the table,
what is f(10)?
E
A
50
0
С
D
60
B
10
2.
3
4
5
6
7
8
9
10 11
Next
Activat
Go to Setto
1002A
3/19/20
CH
O
BH
Type here to search
An
196 becase we all rice
Explanation:
After reading that a solution is a homogeneous mixture, Hala wondered about her favorite
morning drink, grape juice. Which statement about the solution that makes up grape juice is
true? *
1Sugar is one of the solvents, and grapes are one of the solutes.
2Grapes are the solvent and water is one of the solutes.
3Water is the solvent, and sugar is one of the solutes.
4Sugar is the solvent, and water is one of the solutes.
8. If a chemical reaction such as photosynthesis begins with 6 atoms of carbon (C), how many atoms of carbon (C) should be in the products? A. 12 atoms of carbon (C) B. 6 atoms of carbon (C) c. 3 atoms of carbon (C) D. 2 atoms of carbon (C)
A. 12 atoms of carbon (C)
B. 6 atoms of carbon (C)
C. 3 atoms of carbon (C)
D. 2 atoms of carbon (C)
Answer
b
Explanation:
This unit discusses in detail the role of catalysts to lower the activation energy of reactions. The term catalyst appears in nonscientific discussions to refer to something that provokes or speeds significant change or action. Consider this example from the 2006 Associated Press article "Chernobyl cover-up a catalyst for glasnost":
"For the Soviet Union, Chernobyl was a catalyst that forced the government into an unprecedented show of openness that paved the way for reforms leading to the Soviet collapse"
Discuss how this scientific term has made its way into common usage. Does the term catalyst carry the same meaning in regular usage? How is it used differently in a scientific context compared to a nonscientific contexte
Answer:
It can be brought into regular conversation easily I feel it means to "provoke" or "speeds significant change or action" I can see someone saying that in a conversation, "chlorine acts as a catalyst promoting the breakdown of ozone".
I would say it would take the same meaning depending on how you say it and when and what the context of what you're saying it in.
For scientists, it means to change quickly. For someone who says it in a conversation may be saying to stop provoking someone.
Explanation:
Ammonia, nh3, for fertilizer is made by causing hydrogen and nitrogen to react at high temperature and pressure. How many moles of ammonia can be made from 0.15 moles of nitrogen gas? _h2+_02 to _nh3
Answer:
[tex]0.30molNH_3[/tex]
Explanation:
Hello there!
In this case, since the reaction for the formation of ammonia is:
[tex]3H_2+N_2\rightarrow 2NH_3[/tex]
We can evidence the 1:2 mole ratio of nitrogen gas to ammonia; therefore, the appropriate stoichiometric setup for the calculation of the moles of the latter turns out to be:
[tex]0.15molN_2*\frac{2molNH_3}{1molN_2}[/tex]
And the result is:
[tex]0.30molNH_3[/tex]
Best regards!
CaC2(s) + 2H2O(l) --> Ca(OH)2(aq) + C2H2(g) In the reaction above, 0.5487 grams of calcium carbide are completely consumed to produce acetylene gas, C2H2. What volume (in mL) will this gas occupy if it is collected at 43 degrees Celsius and 0.926 atm pressure
Answer:
239.7mL
Explanation:
Using the general gas equation;
PV = nRT
Where;
P = pressure (atm)
V = volume (L)
n = number of moles (mol)
R = gas constant (0.0821 Latm/molK)
T = temperature (K)
The balanced chemical equation in this question is as follows:
CaC2(s) + 2H2O(l) --> Ca(OH)2(aq) + C2H2(g)
From the equation, 1 mole of CaC2 produces 1 mole of ethylene gas, C2H2.
Using mole = mass/molar mass
Molar mass of CaC2 = 40 + 12(2)
= 40 + 24
= 64g/mol
mole = 0.5487/64
mole = 0.00857mol of CaC2
Hence, 0.00857mol of CaC2 produced 0.00857mol of C2H2
Based on the information provided, n = 0.00857mol, T = 43°C = 43 + 273 = 316K, p = 0.926 atm
PV = nRT
V = nRT/P
V = 0.00857 × 0.0821 × 316/0.926
V = 0.222/0.926
V = 0.2397L
In mL, volume = 0.2397 × 1000
= 239.7mL
if 13 moles of Fe react, what is the mass of FeS produced?
Answer:
1144 g of FeS
Explanation:
We'll begin by writing the balanced equation for the reaction. This is illustrated below:
Fe + S —> FeS
From the balanced equation above,
1 mole of Fe reacted to produce 1 mole of FeS.
Therefore, 13 moles of Fe will also react to produce 13 moles of FeS.
Finally, we shall determine mass of 13 moles of FeS. This can be obtained as follow:
Mole of FeS = 13 moles
Molar mass of FeS = 56 + 32
= 88 g/mol
Mass of FeS =?
Mass = mole × molar mass
Mass of FeS = 13 × 88
Mass of FeS = 1144 g
Therefore, 1144 g of FeS were obtained from the reaction.
how many grams of sulphur contain 3.0×1021 atoms
Answer:
There are 0.16 g of sulphur in 3.0 × 10²¹ atoms.
Explanation:
One mole of a substance contains 6.02 × 10²³ particles
One mole of sulphur atom contains 6.02 × 10²³ atoms
Number of moles of sulphur present in 3.0 × 10²¹ atoms = 3.0 ×10²¹/6.02 10²³
Number of moles of sulphur atom = 0.00498 moles of sulphur atom
The mole of a substance is related to its mass by a quantity known as molar mass which is defined as the mass of one mole of that substance.
Molar mass of sulphur atom = 32 grams per mole (g/mol)
Mass of 0.00498 moles of sulphur atom = 0.00498 moles × 32 g/mol
Mass of sulphur = 0.16 g
Therefore, there are 0.16 g of sulphur in 3.0 × 10²¹ atoms.
In a closed system for the reaction: A (g) + 2B (g) → AB₂ (g) The rate of the reaction increases when there is
A) an increase in pressure
B) an increase in the reaction vessel
C) a decrease in the concentration of A
D) an increase in surface area of A
Answer: D
Explanation: an increase in surface area of A
Two rocks one weighing 100m and the other weiging 200n are drpped from a 50-m cliff at the same time when both rocks are 10m from the ground and air friction is ignored which is the same
Answer:
Ignore all friction
When a caterpillar is big enough, it will form a chrysalis. During which stage of metamorphosis does this occur? (2 points) a Adult b Egg c Nymph d Pupa
Answer: The stage of metamorphosis this occurs is called the PUPA stage. The correct option is D.
Explanation:
Metamorphosis can be defined as the change in form, mode of life and behaviour that occurs during embryonic development of an organism. In the metamorphosis of insects, which mostly reproduce sexually, insects can be grouped according to the way the eggs develop into adults. Some show:
--> Complete metamorphosis or
--> Incomplete metamorphosis.
In the life cycle of a butterfly, a COMPLETE metamorphosis occurs. This is because after fertilization, the EGG hatches into LARVA which passes through a PUPAL stage before becoming transformed into an ADULT insect. That is:
Egg --> Larva --> Pupa --> Imago.
When the caterpillar, which is the Larva stage, has reached its full size, it spins a pad of silk on a twig. It moves upward and attached it's clasper to this pad. It spin another silk thread at the thorax. These aids it to assume a slanting position with the head end pointing upwards. The pupa stage called the CHRYSALIS is reached when it tucks it's head under its thorax, arches it's body, shortens and broadens, and moults for the last time. Therefore the correct option is D (pupa).
Answer:
The answer is D. Pupa
19. A piece of unknown metal with a mass of 62.0g and an initial temperature of 95.3°C is dropped into
100.0g of water with an initial temperature of 27.0°C. The final temperature of the system is 34.0°C.
Answer:
a
Explanation:
22) An embryo implants and begins to develop within which structure? *
4 points
Ovary
Oviduct
Cervix
Uterus
Answer:
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