Question:
If $Log_{10}7=0.8451$ then the position of the first significant figure of $7^{-20}$ is
If $Log_{10}7=0.8451$ then the position of the first significant figure of $7^{-20}$ is
Updated On: May 14, 2024
- 16
- 17
- 20
- 15
Hide Solution
Verified By Collegedunia
The Correct Option is B
Solution and Explanation
Let $x=7^{-20}$
$\log _{10} x=-20 \log _{10} 7$
$=-20(0.8451)$
$=-16.902$
Hence, the first significant figure is $17 .$
$\log _{10} x=-20 \log _{10} 7$
$=-20(0.8451)$
$=-16.902$
Hence, the first significant figure is $17 .$
Was this answer helpful?
4
2
Top Questions on Significant figures
- Match List - I with List - II.Choose the correct answer from the options given below :
List - I(Number) List - II(Significant figure) (A) 1001 (I) 3 (B) 010.1 (II) 4 (C) 100.100 (III) 5 (D) 0.0010010 (IV) 6 - JEE Main - 2024
- Physics
- Significant figures
- Time periods of oscillation of the same simple pendulum measured using four different measuring clocks were recorded as 4.62 s, 4.632 s, 4.6 s and 4.64 s. The arithmetic mean of these reading in correct significant figure is.
- JEE Main - 2024
- Physics
- Significant figures
- The minimum value of the function $f(x)=\int\limits_0^2 e^{|x-t|} d t$ is :
- JEE Main - 2023
- Mathematics
- Significant figures
- The minimum value of the function $f(x)=\int\limits_0^2 e^{|x-t|} d t$ is :
- JEE Main - 2023
- Mathematics
- Significant figures
Questions Asked in KCET exam
- Ten identical cells each emf 2V and internal resistance 1Ω are connected in series with two cells wrongly connected. A resistor of 10Ω is connected to the combination. What is the current through the resistor?
- KCET - 2023
- Cells in Series and in Parallel
- The speed of sound in an ideal gas at a given temperature T is v. The rms speed of gas molecules at that temperature is vrms. The ratio of the velocities v and vrms for helium and oxygen gases are X and X' respectively. Then \(\frac{X}{X'}\) is equal to
- KCET - 2023
- Thermodynamics
- If \(p(\frac{1}{q}+\frac{1}{r}),q(\frac{1}{r}+\frac{1}{p}),r(\frac{1}{p}+\frac{1}{q})\) are in A.P., then p, q, r
- KCET - 2023
- Arithmetic Progression
- A stretched wire of a material whose Young's modulus Y = 2 × 1011 Nm-2 has Poisson's ratio of 0.25. Its lateral strain εl = 10-3. The elastic energy density of the wire is
- KCET - 2023
- mechanical properties of solids
- A metallic rod of length 1 m held along east-west direction is allowed to fall down freely. Given horizontal component of earth’s magnetic field BH = 3 × 10-5 T. The emf induced in the rod at an instant t = 2s after it is released is ( Take g = 10 ms-2 )
- KCET - 2023
- Faradays laws of induction
View More Questions
Concepts Used:
Significant Figures
The significant figures of a given number are those significant or important digits, which convey the meaning according to its accuracy. For example, 6.658 has four significant digits. These substantial figures provide precision to the numbers. They are also termed as significant digits.
Rules for Significant Figures:
- All non-zero digits are significant. 198745 contains six significant digits.
- All zeros that occur between any two non zero digits are significant. For example, 108.0097 contains seven significant digits.
- All zeros that are on the right of a decimal point and also to the left of a non-zero digit is never significant. For example, 0.00798 contained three significant digits.
- All zeros that are on the right of a decimal point are significant, only if, a non-zero digit does not follow them. For example, 20.00 contains four significant digits.
- All the zeros that are on the right of the last non-zero digit, after the decimal point, are significant. For example, 0.0079800 contains five significant digits.
- All the zeros that are on the right of the last non-zero digit are significant if they come from a measurement. For example, 1090 m contains four significant digits.