Answer:
true
Explanation:
Which of the following is NOT true of a chemical change?
A. Chemical bonds are broken
B. The identity of a substance has
changed
C. The substance has only
changed form or appearance
D. It can be indicated by the
presence of bubbles or rust
How long will a 25.00 g
sample of americium-241
toke to decay to form a 6.25
g sample of americium-241?
Answer:
Hope it helps.
Explanation:
It decays by beta particle emission into xenon-131. After eight days have passed, half of the atoms of any sample of iodine-131 will have decayed, and the sample will now be 50% iodine-131 and 50% xenon-131
Heavy unstable atoms will continuously emit radiation and will undergo nuclear decay to form stable products. 25 g of americium -241 will take 39 years to decay into its 6.25 g sample.
What is radioactive decay?Heavy unstable nuclei undergo decay when they emit radiations of alpha, beta or gamma particles. After that they will form stable isotopes or other lighter nuclei after emitting these charged particles.
The time an unstable nuclei takes to decay into half of its initial amount is called half life time. The half life time of Americium -241 is 432 years. Thus half life time of 25 g of Am-241 is
= (25 × 432 )/241
= 44.81 years.
The decay constant k can be calculated as follows:
k = 0.693 /half life time
= 0.693 /44.81 yrs
= 0.015.
Now the time taken for the decay process is calculated by the following equation:
t = 1/k log (25/6.25)
= 1/0.015yr-1 log (25/6.25)
= 39 years
Hence, 5 g of americium -241 will take 39 years to decay into its 6.25 g sample.
To find more about radioactive decay, refer the link below:
https://brainly.com/question/1770619
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What is the specific heat of a substance that absorbs 228 joules of heat when a sample of 706 g of the substance increases in tempature from 26.0 c to 88.8 c
Answer:
[tex]c=5.14\ J/kg ^{\circ} C[/tex]
Explanation:
Given that,
Heat absorbed by a sample, Q = 228 J
Mass of a sample, m = 706 g = 0.706 kg
Initial temperature is 26 °C and final temperature is 88.8°C
We need to find the heat absorbed by the sample. The heat absorbed by an object is given by :
[tex]Q=mc\Delta T\\\\\text{Where c is specific heat of sample}\\\\c=\dfrac{Q}{m\Delta T}\\\\c=\dfrac{228\ J}{0.706\ kg(88.8-26)^{\circ} C}\\\\c=5.14\ J/kg ^{\circ} C[/tex]
So, the specific heat of the sample is [tex]5.14\ J/kg ^{\circ} C[/tex].
100 Points Will Make Brainliest. Help Me Please.
I said glasses and gloves first time and it was wrong.
Which of the items shown here will protect you from a chemical burn? Select all that apply.
A hand in a rubber glove.
A fire extinguisher.
A pair of glasses with clear shields attached on the sides.
A power source.
If the glasses and glove were wrong then I would chose the fire extinguisher and the power source should be the correct answer.
That's just what I would do though.
Answer:
rubber gloves and glasses
Explanation:
rubber gloves and glasses
What happens when two positively charged particles are close together? A. They repel each other.
B. They cancel each other.
C. They attract each other.
D. They have no effect on each other.
Answer:
A is the ans
Explanation:
they repel each
ANSWER PLEASE!!
Which one of the following explains why the atom in the diagram
is highly reactive?
option c is correct
number of electron in the outermost shell describe the reactivity if the outermost shell is completely filled its mean the reactivity of element is low and if it is completely filled then the element is highly reactive
I need help please, I will give you five stars
Answer:
The second choice i think
Explanation:
Hope it helps
what is the chemical name of C9F7
Answer:
Chlorogenic acid.
Explanation:
Answer:
chlorofluorocarbons
Explanation:
Which of the following statements is true? a. A technological society has no impact on the environment. b. A technological society has a completely positive impact on the environment. c. A technological society has both a positive and negative impact on the environment d. A technological society has a completely negative impact on the environment. Please select the best answer from the choices provided A B C D
Answer:
The invention of the wheel had an important impact on farming.
Answer:
C
Explanation:
Just took the test
If a block has the mass of 15.00 grams and measurements of 5.00cm by 3.00cm by 2.00cm what is the volume of the block?
Answer:
Volume = 30cm³
Explanation:
A block is a geometrical figure and its volume, -look at the figure-, follows the equation:
Volume = Width*Length*Height
As the measurements of the block are 5.00cm, 3.00cm and 2.00cm, the volume is:
Volume = 5.00cm*2.00cm*3.00cm
Volume = 30cm³2. What was the primary reason in the 1850's driving the curiosity of atoms?
1905-Einstein
1827-Brown
The primary reason that large numbers of people left Ireland in the 1840s and 1850s was MASS STARVATION.
Great Famine or Great Hunger was a period in Ireland where mass starvation, diseases, and emigration occurred between 1845 to 1852.
The Great Famine was caused by Phytophthora infestans, a disease that infests in potatoes. Though the potato infestation spread throughout Europe, it greatly affected Ireland, where 1/3 of its population was dependent on the potato crop as their primary source of food.
The loss of their primary source of food led to mass starvation, sickness, and eventual death. Others opted to leave Ireland and seek shelter and food in other countries to survive.
mass , volume, and density are all properties of what
Answer: Physical properties
Explanation: Can be measured without changing a substance's chemical identity.
What do hydrologists primarily study?
O A. Stars
O B. Rocks
O c. Water
O D. Weather
Where you would find water on Mars
Answer:
Researchers have found evidence of an existing body of liquid water on Mars.
What they believe to be a lake sits under the planet's south polar ice cap, and is about 20km (12 miles) across.
Which of the following is true about scarcity?
Answer:
It would be
a) Scarcity affects all societies.
Which metal would have more luster, zinc (30) or scandium (21)?
Answer:
i say zinc would
Explanation:
Which describes a property of water that allows plants to transfer it from their roots to their leaves?
O Water exhibits weak adhesion and cohesion, which allows capillary action to occur.
O Water exhibits strong adhesion and cohesion, which allows capillary action to occur.
Water has low surface tension, which prevents capillary action from occurring.
Water has high surface tension, which prevents capillary action from occurring.
Answer:
B water exhibits weak adhesion and cohesion which allows capillary action to occur.
Explanation:
took the test
Water exhibits strong adhesion and cohesion, which allows capillary action to occur.
What property of water allows it to move through a plant?The cohesive properties of water (hydrogen bonding between adjacent water molecules) allow the column of water to be 'pulled' up through the plant as water molecules are evaporating at the surfaces of leaf cells. This process has been termed the Cohesion Theory of Sap Ascent in plants.
What are adhesion and cohesion?Cohesion and adhesion are two water properties that describe how water molecules interact with each other. and how water molecules interact with other things like leaves or even you. Cohesion means that water likes to stick to itself and adhesion means that water likes to stick to other things.
Learn more about cohesive properties here https://brainly.com/question/18200549
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54.29
Which statement describes an atomic nucleus?
O An atomic nucleus is negatively charged.
O An atomic nucleus has no electrical charge.
O An atomic nucleus consists of mostly empty space.
O An atomic nucleus contains most of the atom's mass.
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Which is more viscous - petrol or diesel?
Answer:
Petrol....follow me and mark me brainliest
Answer The answer to this question is diesel.
Explanation:
Hi there, hope this helps!
The table shows four samples of carbon dioxide and the temperature of the water that they were dissolved in. Which of the samples most likely had the lowest solubility? I know the answer is sample one (78) but i can't find the right words to explain my answer.
Answer:
Sample 1 = 78°
Explanation:
As per the question, while testing the solubility of a solution comprising of water and carbon dioxide, sample 1 is likely to have the lowest solubility with the temperature of the water being 78°, the maximum. The reason for this result is that the 'solubility of carbon dioxide in the water' falls with an increase in the temperature due to the increase in kinetic energy which will enhance the motion between the molecules and allow them to escape.' Thus, the water with maximum temperature will have the lowest solubility. Hence, sample 1 is the correct answer.
Consider the electron configuration. A box holds an up and a down arrow. A box holds an up and a down arrow. A box holds an up and a down arrow.A box holds an up and a down arrow.A box holds an up and a down arrow. A box holds an up and a down arrow. A box holds an up and a down arrow.A box holds an up and a down arrow.A box holds an up arrow. 1s 2s 2p 3s 3p Which element has this electron configuration? astatine bromine chlorine fluorine
Answer:
Chlorine
Explanation:
Each arrow represents one electron. Most of the boxes are filled, meaning they have two electrons. The last box only has one arrow, so it only has one electron. If you add it up, you get 17, which is Chlorine.
Click here to access the interactive simulation. You will practice balancing chemical equations by playing an interactive game. After accessing the website, select the game box and start with level 1, followed by levels 2 and 3. The goal of these games is to have the same number of atoms on each side of the equation.
In level 1, you balanced the equation N2 + H2 →
NH3. What number did you place in front of ammonia (NH3)?
In level 2, you balanced the equation C + H2O → CH4 +
CO2. What number did you place in front of carbon dioxide (CO2)?
In level 3, you balanced the equation NH3 + O2 → NO2 +
H2O. What number did you place in front of water?
Answer:
In level 1, you balanced the equation N2 + H2 →
✔ 2
NH3. What number did you place in front of ammonia (NH3)?
In level 2, you balanced the equation C + H2O → CH4 +
✔ 1
CO2. What number did you place in front of carbon dioxide (CO2)?
In level 3, you balanced the equation NH3 + O2 → NO2 +
✔ 6
H2O. What number did you place in front of water?
Explanation:
Edge:2020
Answer: 2,1,&6
Explanation: the answer
To separate a mixture of iron filings and salt, the most efficient method would be
Answer:
Explanation:
Of course you could do the separation chemically. Dissolve the salt up in water, pass thru a filter, wash the iron filings with ethanol, which would encourage the salt to precipitate from solution.
I do hope I helped you! :)
Answer:
by passing a magnet through the mixture
Explanation:
The subatomic particle that has a mass equal to the neutron but carries a positive charge is the:
1. Nucleus 2. Electron 3. Proton 4. Neutron
o1 o4 o2 o3
Answer: PROTON
Explanation:
a stable subatomic particle that has a positive charge equal in magnitude to a unit of electron charge and a rest mass of 1.67262 × 10 −27 kg, which is 1,836 times the mass of an electron. Protons, together with electrically neutral particles called neutrons, make up all atomic nuclei except for the hydrogen nucleus (which consists of a single proton).
What are the Oxidation numbers for H2AsO4-
i cant understand your question define briefly
Which object has the lowest density
beach ball
water
sand
A box has dimensions of 2.0 cm time 4.0 cm times 8.0 cm, what is the volume of the box in milliliters?
Answer:
64 mL.
Explanation:
From the question given above, the dimension of box is:
Dimension = 2 cm × 4 cm × 8 cm
Thus, the volume of the box is:
Volume = 2 cm × 4 cm × 8 cm
Volume = 64 cm³
Finally, we shall convert 64 cm³ to mL. This can be obtained as follow:
Recall:
1 cm³ = 1 mL
Therefore,
64 cm³ = 64 cm³ × 1 mL / 1 cm³
64 cm³ = 64 mL
Therefore, the volume of the box in millilitres (mL) is 64 mL.
Will a crayon dissolve in water?
Answer:
Yes
Explanation:Like wax crayons but they can dissolve in water.
Answer:
ye bit
Explanation:
Describing Diffusion
What happens when molecules diffuse across the cell membrane?
The molecules diffuse until all of them are outside the cell.
The molecules move from areas of low concentration to high concentration.
The molecules move from areas of high concentration to low concentration.
The molecules diffuse until all of them are inside the cell.
Answer:
its the 3rd option.
the molecules move from region of higher concentration to a region of lower concentration.
Explanation:
please do give me brainliest if this helped you.
thank you and have a great day :D
Answer:
The molecules move from areas of high concentration to low concentration
Explanation:
How many valence electrons does aluminum (AI) have available for bonding?
1
2
3
4