What is te SI unit of time?
Answer:
second (S) is the SI unit of time.
Answer:
second
Explanation:
the gap between any two intervals is called time
time can be measured in hour,minute,second
but second is the SI unit of time
Write down the constituent elements present in the following compounds.
a. Sodium Sulphate
b. Baking Soda
c. Limestone
d. Bleaching powder
e. Ammonia
f. Caustic Soda
g. Glucose
h. Ammonium Carbonate
I. Acetic acid
j. sulphuric acid
Answer:
in sodium sulphate there is sodium an sulphur
Can someone help me please
relate the pH of a solution to its hydronium and hydroxyl ion concentration and its acidity or basicity
brain list if your answer is good
when ph decrease that means acidity increase
when ph increase that means basicity increase
2. A photon of wavelength for 4 x10 -7 m strikes on the metal surface the work
function of the metal being 2.13 eV.Calculate (i)the energy of the photon in
eV(ii) the kinetic energy of the emission(iii) velocity of the photoelectron
[1ev=1.602x10-19 J]
Answer:
See explanation
Explanation:
Energy of the photon;
E = hc/λ
h= Planks constant
c= speed of light
λ = wavelength
E= 6.6 × 10^-34 × 3 × 10^8/4 x10 -7
E = 4.95 × 10^-19 J
If 1ev=1.602x10-19 J
x = 4.95 × 10^-19 J
x= 3.1 ev
From Einstein's photoelectric equation;
KE = E - Wo
Where;
KE = kinetic energy of ejected photoelectron
E= energy of the photon
Wo= work function of the metal
KE = 3.1 eV - 2.13 eV
KE= 0.97 eV
KE = 0.97 eV × 1.602x10-19 J
KE = 1.55 × 10^-19 J
KE = 1/2 mv^2
1.55 × 10^-19= 1/2 × 9.1 × 10^-31 × v^2
v= √2 × 1.55 × 10^-19/9.1 × 10^-31
v= 5.8 × 10^5 m/s
A new stable element with an atomic number of 120 and an atomic mass of 246 is created in a particle accelerator. Enough of this element is created to determine that it combines with chlorine in a 1:2 ratio. Element 120 should be placed in the same group as _____ on the periodic table.
Answer:
Be,Mg,Ra etc
Explanation:
It should be palced in group 2A because as it reacts with chlorine in ratio of 1:2 . It's valancy is 2 and is metal as it react with non metal donating two electrons .
one more thing it fits there orderly
what is cytoplasm ? what does it contain?
Answer:
Cytoplasm is a thick solution that fills each cell and is enclosed by the cell membrane. It is mainly composed of water, salts, and proteins. All of the organelles in eukaryotic cells, such as the nucleus, endoplasmic reticulum, and mitochondria, are located in the cytoplasm.
Answer:
Explanation:
Cytoplasm is a thick solution that fills each cell and is enclosed by the cell membrane. It is mainly composed of water, salts, and proteins. All of the organelles in eukaryotic cells, such as the nucleus, endoplasmic reticulum, and mitochondria, are located in the cytoplasm. ...
****URGENT****
I need help!!!
the answers are there, i need someone to explain please!
Explanation:
your answer was correct
3. How can you decrease the pressure of a gas in a container without changing the volume of the gas?
add more gas particles to the container
move the container to a lower altitude
o o
reduce the temperature of the gas
O
change the shape of the container
Answer:
reduce the temperature of the gas
Explanation:
when you reduce the temperature of the gas the pressure will decrease
3. An atom
OF
elemente A has mass number 39 and 19 protons
Write the electron arrangement of the atom
Answer:
Explanation:
Potassium (K) atom has 19 electrons. The full electron configuration of Potassium (K) is 1s22s22p63s23p64s1
Principal energy level
Quantum number: n
1
2
3
4
5
6
Sublevels
availableQuantum number: l
1s
2s 2p
3s 3p 3d
4s 4p 4d 4f
5s 5p 5d 5f 5g
6s 6p 6d 6f 6g 6h
what does porous mean
Answer:
porous = allowing liquid or air to pass through slowly
I hope it's helpful
Answer:
It is a rock or or other materials, having minutes interstices through which liquid or air may pass.
Một hỗn hợp X gồm CH3OH; C2H5OH; phenol có khối lượng 28,9 gam phản ứng vừa hết với 100ml dung dịch NaOH 2M. Phần trăm theo khối lượng phenol là ? Biết C = 12; O = 16; H = 1; Na = 23. *
Answer:
nNaOH = 0,2 mol
Trong hỗn hợp các chất đề bài cho chỉ có phenol tác dụng với NaOH
C6H5OH + NaOH → C6H5ONa + H2O
0,2 ← 0,2 (mol)
⟹ mphenol = 0,2.94 = 18,8 gam
⟹
%mC6H5OH=18,8/28,9 x100%= 65,05%
Explanation:
Which statement describes the law of conservation of energy?
All systems will exchange matter and energy with their surroundings.
All systems can exchange energy, but not matter, with their surroundings.
Energy cannot be created nor destroyed, but it changes from one form to another.
Energy is destroyed in most chemical reactions when new products are formed.
Answer:
All systems will exchange matter and energy with their surroundings.
Explanation:
Answer:c
Explanation:
Are you ready kids?
Aye, aye Captain.
I can't hear you!
AYE, AYE CAPTAIN!
Oooooooooh.
Who lives in a pineapple under the sea?
Spongebob squarepants!
Absorbent and yellow and porous is he?
Spongebob squarepants!
If nautical nonsense be something you wish!
Spongebob squarepants!
Then drop on the deck and flop like a fish!
Spongebob squarepants!
Ready?
Spongebob squarepants.
Spongebob squarepants.
Spongebob squarepants.
Spongebob squarepants.
Spongebob-squarepants.
Some species form social groups only with members of the same gender. For example, elephants form groups with
only females and their offspring. Once the male offspring reach a certain age, they leave the group and become
solitary.
Which is a benefit of this type of social group structure?
Explanation:
For example, elephants form groups with only females and their offspring. Once the male offspring reach a certain age, they leave the group and become solitary. Which is a benefit of this type of social group structure? A:Females do not have to compete for a mate.
The addition of solute particles into a solution causes:
A. the solvent particles to be attracted to the solute particles and to have less kinetic energy.
B. the solute particles to bump the solvent particles out of the solution, making it easier to boil.
C. the solute particles to form seed crystals and make the solution freeze more easily.
D. the solvent particles to be spread further out and have more to move, increasing their kinetic energy.
Answer:
D. the solvent particles to be spread further out and have more to move, increasing their kinetic energy.
Explanation:
The addition of solute particles results in an increased boiling point. As the solutes increases so does the energy inside as the solutes add and occupies more space near the surface of the liquid.Balance the following equations
ANSWER
2Ba + 2HBr → 2BaBr + H2
2BiCl3 + 3H2S → Bi2S3 + 6HCl
Br2 + 2KI → I2 + 2KBr
4Fe + 3O2 → 2Fe2O3
I HOPE THIS WILL HELP YOU IF NOT THEN SORRY HAVE A GREAT DAY:)Answer:
[tex]3Mg _{(s)} + N _{2(g)} → Mg_{3} N _{2(s)}[/tex]
[tex]Ba _{(s)} + 2HBr_{(g)} → BaBr _{2(s)} + H _{2(g)}[/tex]
[tex]2BiCl_{3(s)} + 3H_{2} S _{(g)} → Bi _{2} S _{ 3(g)} + 6HCl _{(g)} \\ [/tex]
[tex]Br_{2(g)} + 2KI _{(g)} → I _{2(g)} +2 KBr _{(g)}[/tex]
[tex]4Fe_{(s)}+ 3O_{2(g)} → 2Fe_{2} O _{3(s)} [/tex]
Which of the following is an example of combustion?
O A. potassium chlorate -> potassium chloride + oxygen
B. aluminum + cobalt chloride -> aluminum chloride + cobalt
O c. hexane + oxygen carbon dioxide + water
OD. sodium cyanide + hydrochloric acid -> sodium sulfate + hydrogen cyanide
Which of the following would not be considered matter?
clouds
trees
rain
air
light
Answer:
light
Explanation:
Have a nice day
Answer:
light
Explanation:
2. 10.00 grams of a sample of hydrated PtCl4 are heated and lose 3.00 g of water. How many moles of water are combined with each mole of PtCl4?
Answer:
8 mol
Explanation:
Step 1: Calculate the mass of PtCl₄ in the sample
10.00 grams of a sample of hydrated PtCl₄ are heated and lose 3.00 g of water. The mass of PtCl₄ is:
mPtCl₄ = 10.00 g - 3.00 g = 7.00 g
Step 2: Calculate the moles corresponding to 7.00 g of PtCl₄ and 3.00 g of H₂O
The molar mass of PtCl₄ is 336.9 g/mol.
7.00 g × 1 mol/336.9 g = 0.0208 mol
The molar mass of H₂O is 18.02 g/mol.
3.00 g × 1 mol/18.02 g = 0.166 mol
The molar ratio of H₂O to PtCl₄ is:
0.166 mol H₂O/0.0208 mol PtCl₄ ≈ 8 mol H₂O/ 1 mol PtCl₄
Câu 9: 100 g dung dịch MgCl2 9.5 % tác dụng đủ với dung dịch KOH 5,6 % .được dung dịch A và chất rắn B. Lọc rắn B và nung đến khối lượng không đổi được chất C.
a) Viết pt .Tính khối lượng răn C
b) Tính nồng độ phân trăm của dung dịch A.
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A sample of gas occupies 1.2 L at 12.0oC. Assuming pressure remains the same, what would be the volume (in L) of this gas at 67oC?
A.
1.4
B.
1.0
C.
0.2
D.
5.0
E.
6.7
Answer:
e.
6.7
hope it help
.
.
.
.
.
.
Unknown # 21
Flame Test Color: Lilac
Addition of HCl(aq)= NR (No Reaction)
Addition of HCl(aq) and BaCl2(aq)= White precipitate
Addition of HNO3(aq) and AgNO3(aq)= NR (No Reaction)
What is the unknown ionic compund molecular formula?
Uranium-235 and uranium-238 are different ________ of uranium
(Apx answers please)
Answer:
Isotopes
Explanation:
An isotope are the atoms of an element with similar chemical identity and number of protons but different atomic masses. This means that isotopes of an element differ from one another by their number of NEUTRONS.
For example, the uranium element possesses isotopes as follows: Uranium-235 and uranium-238. This two isotopes have the same chemical identity and number of protons/atomic no., which is 92. However, the atomic masses (235 and 238) are different.
Answer:
Isotopes
Explanation:
Which atom's ionization energy is greater than that of phosphorus (P)?
A. Ba
B. K
C. As
D. CI
Answer:
Chlorine
Explanation:
the ionization increases as you get closer to the top right. since chlorine (Cl) is the only one of the answer choices that is closer to the top right corner compared to phosphorous (P), that is the answer.
Answer:
cl
Explanation:
because ionization energy decrease from left to right
Which of these solutions is acidic?
Answer:
Option a is a solution acidic ([OH⁻] = 7.0x10⁻⁹ M).
Explanation:
To know if a solution is acidic we need to calculate the pH and it must be lower than 7. A value of pH equal to 7 is a neutral solution and a solution with a pH value higher than 7 is a basic solution.
a. For the [OH⁻] = 7.0x10⁻⁹ M we have:
[tex] pOH = -log[OH^{-}] = -log(7.0 \cdot 10^{-9}) = 8.15 [/tex]
Now, the pH is:
[tex] pH + pOH = 14 [/tex]
[tex] pH = 14 - pOH = 14 - 8.15 = 5.85 [/tex]
This solution is acidic (pH < 7)
b. [H₃O⁺] = 8.5x10⁻⁸ M
[tex] pH = -log(8.5 \cdot 10^{-8}) = 7.07 [/tex]
This is not an acidic solution. Is a neutral one (pH around to 7).
c. [OH⁻] = 2.5x10⁻⁶ M
[tex] pOH = -log[OH^{-}] = -log(2.5 \cdot 10^{-6}) = 5.60 [/tex]
Then, the pH is:
[tex]pH = 14 - pOH = 14 - 5.60 = 8.40[/tex]
Hence, this is not an acidic solution. It is basic (pH > 7).
Therefore, option a is a solution acidic ([OH⁻] = 7.0x10⁻⁹ M).
I hope it helps you!
In ionic bonding Question 41 options: the electrons are shared between the atoms. the process of forming an ionic bond is highly endothermic overall. the bonding that occurs is usually between two nonmetal atoms. a noble gas configuration is formed for each element or ion. At least two of the above statements are correct.
Answer: In ionic bonding (a noble gas configuration is formed for each element or ion).
Explanation:
IONIC bonding, which is also called electrovalent bonding involves the complete transfer of electrons from one atom to another in order to attain a noble gas electron configuration.
The noble gases or group 0 elements have a completely filled outermost shell of eight electrons. This makes them generally very stable, that is, unreactive. There is a natural drive for other atoms to attain the electron configuration of group 0 (inert gases) elements. This usually results in atoms entering into chemical combinations by losing, gaining or sharing electrons.
Ionia compound such as sodium chloride
--> have high melting points because alot of heat energy is required to break the attractive forces between the ions;
--> are hard and brittle;
--> are soluble in water;
--> conduct electricity when in solution or molten form because the ions are able to move about, that is, they are electrolytes
What is an atomic mass unit? Write down the electric charge of proton neutrons and electric.
Answer:
protons has a positive charge.
Neutrons does not have a charge (neutron = neutral)
Electrons has a negative charge
6c.Calculate the maximum volume, in dm3, of chlorine gas at Stp that can be obtained from 23.4 tonnes of molten sodium chloride. 1 tonne= 10^6 Mr of NaCl=58.5 molar volume of chlorine at stp= 24dm3 Give your answer in standard format.
Answer:
4.48×10⁶ dm³
Explanation:
We'll begin by converting 23.4 tonnes to grams (g). This can be obtained as follow:
1 tonne = 10⁶ g
Therefore,
23.4 tonnes = 23.4 × 10⁶
23.4 tonnes = 2.34×10⁷ g
Thus, 23.4 tonnes is equivalent to 2.34×10⁷ g
Next, we shall determine the number of mole in 2.34×10⁷ g of NaCl. This can be obtained as follow:
Mass NaCl = 2.34×10⁷ g
Molar mass of NaCl = 58.5 g/mol
Mole of NaCl =?
Mole = mass / molar mass
Mole of NaCl = 2.34×10⁷ / 58.5
Mole of NaCl = 4×10⁵ moles
Next, we shall determine the number of mole of chlorine, Cl₂ produced from the reaction. This can be obtained as follow:
2NaCl —> 2Na + Cl₂
From the balanced equation above,
2 moles of NaCl reacted to produce 1 mole of Cl₂.
Therefore, 4×10⁵ moles of NaCl will react to produce = (4×10⁵ × 1)/2 = 2×10⁵ moles of Cl₂.
Thus, 2×10⁵ moles of Cl₂ were obtained from the reaction.
Finally, we shall determine the volume of Cl₂ produced. This can be obtained as follow:
1 mole of Cl₂ at stp = 22.4 dm³
Therefore,
2×10⁵ moles of Cl₂ at stp = 2×10⁵ 22.4
2×10⁵ moles of Cl₂ at stp = 4.48×10⁶ dm³
Thus, the volume of chlorine obtained from the reaction is 4.48×10⁶ dm³
Suppose you had a valuable collection of small diamonds, which you kept safe from the thieves by mixing them with white sugar crystals. You store the mixture in a jar labeled 'sugar'. Now you want to sell the diamonds. Describe how you would separate all the diamonds from the sugar.
Answer:
Pour the sugar/diamond mixture into a container of water and stir until the sugar is dissolved completely. Then strain the mixture and wash the diamonds with water.
Answer:
Stir with a large enough volume of cold water to dissolve all the sugar. Filter to leave the diamonds on the filter paper. Wash on the filter paper with more water to remove any last traces of sugar solution. Allow to dry.
A scientist claims that the water molecules that you drink today could be millions of years old. Use evidence from the water cycle to support the scientist’s claim.
Answer:
As water on the surface of lakes, oceans, and rivers warms up, it travels into the sky as very tiny droplets, or vapor. When the water vapor gets colder, it turns back to liquid to help form clouds.
When the liquid gets so heavy it can’t stay in the atmosphere anymore, it falls, or “precipitates,” as rain, snow, sleet, hail, or, my favorite, graupel. Once the precipitation reaches the ground or lands in lakes, oceans, and rivers, the cycle continues.
Explanation:
A scientist claims that the water molecules that you drink today could be millions of years old in the water cycle the new clouds athat re made cannot rain but the clouds which are old do rain.
What is the water cycle?The water cycle or cycle of water is the journey of each and every water molecule by which it is made up of as the clouds in the environment are made up of the evaporation process in the environment.
The vapors of evaporation condense in the environment to form the clouds and these clouds are only responsible for the rain but the old and heavy clouds can only do it.
Therefore, in the water cycle, the new clouds are made cannot rain but the clouds which are old do rain scientist claim that the water molecules that you drink today could be millions of years old.
Learn more about the water cycle, here;
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