Older pewters with a higher lead content weigh more, tarnish more quickly, and develop a darker silver-grey colour with time. Through BS5140, which was strengthened by BSEN611 in 1994, lead was eliminated from the composition in 1974.
What is Lead ?
The periodic table's element lead has an atomic number of 82.
Humans have used lead (Pb), a metal, for countless years, going all the way back to 7000 BC.
The element can be found in trace amounts in a number of minerals, with the exception of sulphide and lead glance (PBS), which are used to make the metal all over the world.
Lead (Pb) is a white, soft, shiny metal that is very malleable.
The metal is not only a good conductor of electricity but also has a strong resistance to corrosion.
When burned in the air, the metal's powdered form emits a bluish-white blaze.
Lead fluoride is created when fluorine and lead are combined at ambient temperature.
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Scientists have been able to find a full record of Earth's fossil history, thus making the fossil record complete.
True or False?
Answer:
False
Explanation:
Few organisms were not preserved as well as others, and new fossils are found every day
a solution is prepared by dissolving 55g of CaCl2 into 300g of water. if the Kf of water is -1.86 c/m, shat is the freezing point depression of the solution
Answer:
Relation between , molality and temperature is as follows.
T =
It is also known as depression between freezing point where, i is the Van't Hoff factor.
Let us assume that there is 100% dissociation. Hence, the value of i for these given species will be as follows.
i for = 3
i for glucose = 1
i for NaCl = 2
Depression in freezing point will have a negative sign. Therefore, d
depression in freezing point for the given species is as follows.
=
=
=
Therefore, we can conclude that given species are arranged according to their freezing point depression with the least depression first as follows.
Glucose < NaCl <
Explanation:
A train with an initial velocity of 31 m/s begins accelerating at rate of 0.0705 m/s^2. If the train travels for 180.5s, how far does it travel?
Answer:
v = 43.72 m/s
Explanation:
Given that,
Initial velocity of the train, u = 31 m/s
Acceleration of the train, a = 0.0705 m/s²
Time for which the train travel, t = 180.5 s
We need to find the final velocity of the train. Let it is v.. Using first equation of kinematics to find it such that,
[tex]v=u+at\\\\v=31+0.0705\times 180.5\\\\v=43.72\ m/s[/tex]
So the final speed of the train is equal to 43.72m/s.
qestions do you have about plate tectonics
From the deepest ocean trench to the tallest mountain, plate tectonics explains the features and movement of Earth's surface in the present and the past.
Developed from the 1950s to the 1970s, the theory of plate tectonics is the modern update to continental drift, an idea first proposed by scientist Alfred Wegener in 1912 which stated that Earth’s continents had “drifted” across the planet over time. Wegener didn't have an explanation for how continents could move around the planet, but researchers do now: plate tectonics.
Plate tectonics is the theory that Earth's outer shell is divided into large slabs of solid rock, called “plates,” that glide over Earth's mantle, the rocky inner layer above Earth’s core. Earth’s solid outer layer, which includes the crust and the uppermost mantle, is called the lithosphere. It is 100 km (60 miles) thick, according to the Encyclopaedia Britannica. Below the lithosphere is the asthenosphere—a viscous layer kept malleable by heat deep within the Earth. It lubricates the undersides of Earth's tectonic plates, allowing the lithosphere to move around.
Answer:
1. How fast do tectonic plates move? Answer: There are seven major plates: African, Antarctic, Eurasian, Indo-Australian, North American, Pacific and South American
2. What are the factors affecting plate tectonics? Answer: The force that causes most of the plate movement is thermal convection, where heat from the Earth's interior causes currents of hot rising magma and cooler sinking magma to flow, moving the plates of the crust along with them.
3. What 3 things support the theory of plate tectonics? Answer: Modern continents hold clues to their distant past. Evidence from fossils, glaciers, and complementary coastlines helps reveal how the plates once fit together. Fossils tell us when and where plants and animals once existed.
Explanation:
What is the value that is MEASURED in a lab?
Answer:
To use standard laboratory measurement devices to measure length, volume and mass amounts.
What type of organism is the common house cat?
F
parasite
G
saprophyte
H
autotroph
J
heterotroph
Answer:
F
parasite
Explanation:
Select the correct answer.
John is riding a ski lift to the top of Wildcat Mountain. He removes his gloves and rapidly rubs his hands together to warm them up. What
happens when John rubs his hands?
O A. The skin on his hands rapidly conducts heat, similar to metal.
O B. He traps heat between his hands because skin is an insulator. IS
O C. The particles In his hands vibrate faster because of friction.
O D. Thermal energy moves from his fingertips to his palms.
O E. He simulates a fever that'll raise his core body temperature.
Answer:
Fairly certain it's C. The particles In his hands vibrate faster because of friction :)
Answer:
C
Explanation:
An 886 mL sample of Neon gas is at 752 torr and 299 K. What will be the new volume if, with the pressure and amount of gas held constant the temperature is increased to 371 K?
Answer:
[tex]V_2=1099.35mL[/tex]
Explanation:
Hello there!
In this case, according to the given information, it is possible to infer that as both the amount of the gas and the pressure remains the same, we can solve this problem via the Charles' law a directly proportional relationship between the volume and temperature:
[tex]\frac{V_2}{T_2} =\frac{V_1}{T_1}[/tex]
Thus, by solving for the final volume, V2, we obtain:
[tex]V_2 =\frac{V_1T_2}{T_1} \\\\V_2 =\frac{886mL*371K}{299K}\\\\V_2=1099.35mL[/tex]
Best regards!
WILL MARK BRAINLIEST!!
Need help plsss
6.32 KJ is how much heat is given off
a- Write the name of the process when the electron falls to a lower energy level and a photon is emitted
Answer:
emission
Explanation:
when atoms return to lower energy levels they emit photons, in a process called emission
what is the ionic equation for dilute hydrochloric acid and magnesium
Answer:
Mg(s) + 2H⁺(aq) ⟶ Mg²⁺(aq) + H₂(g)
Explanation:
A net ionic equation shows all the ionic substances as ions and shows the correct state of each substance.
Magnesium react with hydrochloric acid according to the equation :
Mg(s)+2HCL(aq)----->MgCL2(aq) +H2(g)
This demonstration can be used to illustrate the characteristics reactions of metals with acid , a single replacement reaction ,or to demonstrate the generation of hydrogen gas.
Describe how urine is formed, beginning with the blood. In 5th grade language please
Answer:
kidneys takes the waste out of the blood. It is then stored in the bladder, until the urinary tract takes the urine out of the body.
A student titrated 50 cm of sulphuric acid (H2SO4)of an unknown concentration
in a flask with sodium hydroxide (NaOH).
The acid required 30 cm3 of 0.500 mol/dm3 NaOH to reach the end point
H2SO4(aq)
+ 2NaOH(aq)
Na2SO4(aq) + 2H2O()
Calculate the concentration the acid.
Concentration =
mol/dm3
The mass of this atom is:
u. 3 mass units
b. 4 mass units
c. 6 mass units
d. 7 mass units
e. 11 mass units
What does the little 2 in 2CO2 mean?
Answer:
it means 2 oxygen atoms in the molecule
Explanation:
Can someone please answer this?
Answer:
B) go look on the periodic table for the atomic number
Explanation:
The atomic number is how many protons is in an atom
Answer:
Either A or B
Explanation: Because I learned it on Edge. :)
9
If you wanted to make 250 mL of a 0.01 M solution of CaCl, calculate how many moles of calcium chloride would be
needed. Your response must include both a correct numerical setup and the calculated result. [1]
Answer:
0.0025moles
Explanation:
Molarity of a solution (M) = number of moles (n) ÷ volume (V)
According to this question, to make 250 mL of a 0.01 M solution of CaCl, the following number of moles is needed:
Volume = 250mL = 250/1000 = 0.250Litres.
Using; molarity = n/V
0.01 = n/0.250
n = 0.0025
n = 2.5 × 10^-3 moles.
An oxidizing flame resembles the neutral flame slightly, but has an inner cone that is shorter and more pointed with an almost purple color instead of brilliant white true or false
Answer:
True
Explanation:
The answer to this question is true. The oxidizing flame is a flame which is gotten when oxygen is used excessively. The flame is bluish or almost purple in color. And it makes a hissing sound. The flame from this is shorter than the neutral flame. In the neutral flame there is neither the occurrence of oxidation or reduction.
What is the percent by mass of C in benzene (C6H6)? The molecular weight of carbon is 12.0107 g/mol and of hydrogen 1.00794 g/mol
Answer:
92.26% of C
Explanation:
To solve this problem we must assume we have 1 mole of benzene. The mole contains 6 moles of C and 6 moles of H. We have to convert these moles to grams in order to find the total mass and mass percent will be:
Mass atom / Total mass * 100
Mass C: 6mol C * (12.0107g / mol) = 72.0642g
Mass H: 6mol H * (1.00794g / mol) = 6.04764g
total mass: 72.0642g + 6.04764g = 78.11184g
Mass percent of C will be:
72.0642g C / 78.11184g* 100
92.26% of CPLSSS ANSWERRRRR????
Please Help! Brainliest!
Convert the following to milligrams: 5.6 x 10-4 kilograms. Show your work on a separate sheet of paper and attach
with your assignment.
Hi there!
Here's a picture to show you. Does this help?
How many milliliters of 0.20 M NaOH must be added to 75 mL of 0.050 M HCl to make a neutral solution?
Answer:
this should help
Explanation:
People don't want to live in a warming world so maybe do less things that emit greenhouse gasses.
Answer:
yea that's true
things you can do is: reduce ,reuse, and recycle
reduce the use of air/heat
remove lightbulbs and replace led bulb
drive less
plant a tree
Explanation:
Which energy transformation occurs when a match is lit?
A
Chemical energy to heat energy
B
Heat energy to potential energy
C
Electrical energy to heat energy
D
Kinetic energy to potential energy
Answer:
A
Explanation:
the chemical energy in the phosphorous in the match turns into heat energy once the match is struck and starts to combust.
What theoretical yield of NaCl would result from reacting 3.00 moles of Na2CO3 with excess HCl (aqueous)?
Answer:
350.7 g of NaCl
Explanation:
For this reactions our reactants are:
HCl and Na₂CO₃.
Then, the reaction is:
2HCl + Na₂CO₃ → 2NaCl + H₂CO₃
2 moles of hydrochloric acid react to 1 mol of sodium carbonate in order to produce 2 moles of salt and 1 mol of carbonic acid.
Ratio is 1:2. 1 mol of sodium carbonate can produce 2 moles of NaCl
Then, 3 moles of carbonate may produce (3 . 2) /1 = 6
We convert the moles to mass to determine the theoretical yield
6 mol . 58.45g /mol = 350.7 g
The theoretical yield of NaCl produced is 350.7 g.
What is NaCl?NaCl is a salt, and it is an ionic compound.
The reaction is
[tex]\rm 2HCl + Na_2CO_3 \rightarrow 2NaCl + H_2CO_3[/tex]
2 mol of HCl reacts with 1 mol of [tex]Na_2CO_3[/tex] and produces 2 mol of NaCl and 1 mol of [tex]H_2CO_3[/tex].
The ratio will be [tex]Na_2CO_3[/tex] : NaCl
1 : 2
Then, for 3 mol of [tex]Na_2CO_3[/tex]
[tex]\dfrac{3 \times 2}{1} = 6[/tex]
Now, convert the moles to mass
[tex]6\; mol \times 58.45g /mol = 350.7 g[/tex]
Thus, the theoretical yield produced is 350.7 g.
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How many moles of nitrogen gas are present in a 28.9 dm3 temperature of 55.0 °C and a pressure of 144 kPa?
Given :
Temperature, T = 55° C = ( 55 + 273 ) K = 328 K .
Volume of container, V = 28.9 dm³ = 0.0289 m³ .
Pressure, P = 144 kPa = 144000 Pa .
To Find :
Number of moles of nitrogen gas.
Solution :
We know, by ideal gas equation :
PV = nRT ( R ( universal gas constant ) = 8.31 J K⁻¹ mol⁻¹ .
[tex]n = \dfrac{PV}{RT}\\\\n = \dfrac{144000\times 0.0289}{8.31 \times 328} \ moles\\\\n = \dfrac{4161.6}{2725.68}\\\\n = 1.53 \ moles[/tex]
Therefore, number of moles of nitrogen gas is 1.53 moles.
The picture shows a community living in a dry, grassy area. A few organisms have died off due to lack of a water source. ******Is this an example of an abiotic or biotic limiting factor? WHY
Answer:
brainly blurred the half of the question i cant read it completely
Explanation:
Answer correctly and dont bother coming to this question if you have the wrong answer.
Answer:
it's b or d I am not 100% sure witch one tho
Answer:
B.
Explanation:
It is B because it says which is an example of A PHYSICAL MODEL. B is a physical model becuase by using tennis balls to represent the plantes (including the sun)
it is a model of a problem!!!
Have a great day!
Hope this helps!
-Lea
Create a model of the atoms of a substance moving through the solid, liquid, and gas states.
what is the electronic structure of an atom with a proton number 11 and mass number 23
Answer:
1s^2 2s^2 2p^6 3s^1
Explanation:
electron configuration of an element gives description of the distribution of electron in it's orbital of the atom, the superscript symbolize number of electron been hold by them.
The element here is sodium, which is a alkali metal
mass number =23
Number of proton= 11
electron must be seen in thelowest-energy subshell that is available in the the 3s orbital,
Hence, the electronic configuration is
1s^2 2s^2 2p^6 3s^1