WorksheetsIJSO
Total questions: 29
Worksheet time: 1hrs 29mins
Bats use ultrasonic waves to catch prey. When stationary, a bat emits ultrasonic waves of frequency 82.5 kHz. The bat now starts following a moth along the +x direction. The speeds of the bat and moth are 9.00 m/s and 8.00 m/s, respectively. The bat now emits and detects the wave reflected by the moth. The velocity of sound is 340 m/s. Which of the following is the closest frequency for the detected wave by the bat?
82.7 kHz
82.8 kHz
82.9 kHz
83.0 kHz
A 15 kg mass is pulled along a horizontal frictionless surface with a component of force of 40 N along the east and a component of 30 N along north. What is the magnitude and direction (with respect to the east) of the acceleration of the mass?
4.33 𝑚 𝑠 −2 𝑎𝑡 𝑎𝑛 𝑎𝑛𝑔𝑙𝑒 𝑜𝑓 37𝑜
3.33 𝑚 𝑠 −2 𝑎𝑡 𝑎𝑛 𝑎𝑛𝑔𝑙𝑒 𝑜𝑓 37𝑜
3.33 𝑚 𝑠 −2 𝑎𝑡 𝑎𝑛 𝑎𝑛𝑔𝑙𝑒 𝑜𝑓 67�
8.33 𝑚 𝑠 −2 𝑎𝑡 𝑎𝑛 𝑎𝑛𝑔𝑙𝑒 𝑜𝑓 67�
A light source device located on point A produces an incident light which is reflected by a mirror with the configuration as shown in the following Figure. An object which is located on the point B is aimed to be a target of the reflected light. If the horizontal distance of the object in the point B to the mirror is 2.20 m, the vertical distance between A and B (H), and between A and the point of reflection (h) are 1.68 m and 0.430 m respectively, find the horizontal distance (x) between the light source device (A) and the mirror.
0.381 m
0.757 m
1.04 m
1.42 m
During Qatar marathon 2019, an ambulance with a speed of 3.00 m/s and siren frequency of 5.00×102 Hz passes by an athlete running with a speed of 4.00 m/s as shown in the figure. What would be the change in the frequency perceived by the runner as the ambulance passes by him. The speed of sound in air 343 m/s .
−0.760×102 Hz
0.990×102 Hz
−0.890×102 Hz
0.850×102 Hz
Given that the universal gravitational constant, G = 6.7 × 10-11 Nm2 kg-2 and that the mass, M of the earth is 6.0 × 1024 kg, find the speed of a satellite that is fixed to permanently focus on the city of Abuja for broadcast of the 2010 IJSO competition.
3.08 × 103 ms-1
24 ms-1
40 ms-1
3.66 × 103 ms-1
A 40 kg girl and an 8.4 kg sled are on surface of a frozen lake, 15 m apart. By means of a rope, the girl exerts a horizontal force on the sled, pulling it toward her. How far has the girl traveled when she meets the sled, assuming that no frictional force acts?
2.0 m
4.4 m
3.8 m
2.6 m
An image is located at exactly the same position as its object, for a concave mirror of focal length 8 cm. What is the object distance from the mirror?
16 cm
8 cm
24 cm
4 cm
In electromagnetic spectrum _________ waves have the largest wavelength and __________ waves have the smallest wavelength. What should be written in the blanks respectively?
Gamma – Radio
Radio – Gamma
Infrared – Gamma
adio - Ultraviolet
The table shows different types of wave in the electromagnetic spectrum. Where do all the waves travel at the same speed?
In a vacuum
In diamond
In glass
In water
Despite the fact that the Earth-Sun distance is much larger than the Earth-Moon distance, the gravitational force exerted by the Sun on Earth is larger than the gravitational force exerted by the Moon o Earth. However, it is the Moon, and not the Sun, the main factor responsible for the high tides here on Earth. Why is that the case?
Because of the revolution of the Moon around the Earth
Because the mass of the Earth is more similar to the mass of the Moon
Because the gravitational force the Moon exerts on Earth is more nonhomogeneous
Because the angular diameter of the Moon, as seen from Earth, is smaller than that of the Sun
Several indicators are used to determine the pH of river water sample. If an indicator was added to the sample, the color of indicators added to the water sample is shown below:
3.1 < pH < 7.0
4.4 < pH < 7.6
6.0 < pH < 8.3
7.6 < pH < 8.3
Which of the following is the correct order of the decreasing ionic radius for Na+, Mg2+, O2−, and F − ?
Na+ > Mg2+ > F− > O 2−
Mg2+ > Na+ > O2− > F –
O2− > F − > Na+ > Mg2+
F− > O2− > Mg2+ > Na+
In a chemical reaction, when calcium changes (atomic number, Z = 20) to form calcium ions, the ions react with carbonate ions. In this reaction each calcium atom:
releases one electron
releases two electrons
gains two electrons
increases atomic number by two
If the first bulb is filled by CO gas with pressure of 2 atm and the second bulb is filled by O2 with pressure of 1 atm. The valve is opened, the gas CO in the first bulb and gas O2 in the second bulb would mix and react completely according to the following reaction: 2 CO (g) + O2 (g) ® 2 CO2 (g) After reaction take place completely, the gas in both bulbs consist of:
CO, O2, and CO2
CO and CO2
O2 and CO2
only CO2
For the oxidation–reduction reaction;
K2Cr2O7 + XH2SO4 +YSO2 → K2SO4 + Cr2(SO4)3+ZH2O
The values X, Y and Z are:
1, 3,1
4,1,4
3,2, 3
2,1,2
The following figure shows the heating curves of two liquids A and B obtained by measuring temperatures (T) as a function of time using a burner with a constant heating rate. Suppose that two liquids have the same mass. Which one of the following statements is correct?
The boiling point of B is larger than that of A.
The specific heat capacity of gas is greater for B than for A.
The heat of vaporization per gram of liquid for A is greater than that for B.
The specific heat capacity of gas is greater than that of liquid for substance B.
. 0.2 M aqueous solution of an unknown salt shows a precipitate when treated with barium nitrate solution and turns a phenolphthalein solution pink. The unknown substance could be:
NaCl
K2CO3
(NH4)2SO4
SrCl2
We can classify substances according to the conductivity of their solutions. Strong electrolytes (1) conduct electric current very well. The substances that conduct electric current poorly are called weak electrolytes (2); the non – electrolytes (3) do not conduct current at all.
I. 1M CH3COOH II. 1M C12H22011
III. 1M KNO3 IV. 1M NH3
Which of the following matching is correct? (Hint: the strength of an electrolyte is directly proportional to its ability to separate into ions, but not to its ability to dissolve)
I – 2, II – 2, III – 1, IV – 3
I – 3, II – 2, III – 1, IV – 2
I – 2, II – 3, III – 3, IV – 2
I – 2, II – 3, III – 1, IV – 2
Which of the following two properties best describe non – metals?
Low ionization energy and good electrical conductivity.
High ionization energy and poor electrical conductivity.
Low ionization energy and poor electrical conductivity.
High ionization energy and good electrical conductivity.
A woman who has four sisters married to a man who has three brothers and one sister. What is the usual probability of having a son if they have a child?
12.5%
25%
50%
75%
Look at the picture carefully! The secondary and the tertiary consumers are:
Frog, snake
Frog, eagle
Snake, eagle
Fox, snake
The information of the physical world outside our body, as well as the processes inside, is collected by sensory receptors. Most of these receptors are specialized neurons or epithelial cells, existing in single or groups with other types of cells within the sensory organs. Choose the correct match among organs, sensory cells and receptor types from the table below.
I, 1, b
II, 2, c
III, 3, a
IV, 4, d
In general, plants have a much larger surface area/volume ratio. What is the main reason for this?
The advantages of having a larger body surface in plants are correlated to the area of light absorption.
Plants, in general, are bigger than animals.
Animals need a larger volume in order to store water.
Animals have more complex chemical substances in their bodies.
Regarding the functions of the stomach, which ones of the following statements
are true?
(1) digestion and decomposition of proteins
(2) digestion and absorption of fat
(3) killing of most bacteria in food
(4) storage of partial digested food
1, 2
1, 3
2, 4
2, 3
The pathways and reactions involved in the nitrogen cycle are complicated. The following describes some parts of the nitrogen cycle.
Which of the following options from A to D chooses all the correct statement(s) from the box?
①, ②
①, ③
②, ③
②, ④
Consider a hypothetical population, where all members have access to abundant food and they are free to reproduce at their physiological capacity. Which one of the following curves best represents the population growth expected under such conditions?
In an eukaryotic cell, mitochondria and chloroplasts are thought to have originated through endosymbiosis, a process in which an organism engulfs another and the two continue to exist in a mutually beneficial arrangement. Which of the following observations best supports this theory?
These organelles exchange metabolites with other cellular compartments.
These organelles are capable of independent existence outside the cell.
These organelles have their own genetic material.
These organelles provide energy in the form of ATP to the cell.
Charles Darwin observed that seedlings grow towards light. He called this response ‘phototropism.’ In an experiment two light sources are used to illuminate each seedling. Each source is indicated by a yellow circle in the diagrams below. The larger yellow circle represents a light source with twice the illumination than the light source represented by the smaller yellow circle.
Which of the above responses would be observed?
only (iv)
only (ii)
(i) and (iii)
(i) and (iv)
Why can a person not swallow food and talk at the same time?
The brain cannot control two activities at the same time.
In order to speak, air must come through the pharynx to form sounds.
In order to swallow, the epiglottis must close off the larynx (trachea).
Both B and C are correct.
