Explanation

Rose petals act as a natural pH indicator.

They turn blue in alkaline (basic) solutions due to pigment changes.

Explanation

Personification is giving human qualities to non-human things — here, "stairs groaned" gives human action to stairs.

It creates imagery by making the object (stairs) seem alive.

Explanation

Given:

logx(0.001) = -3

This can be rewritten as:

x^(-3) = 0.001

0.001 = 10^(-3)

So:

x^(-3) = 10^(-3)

This implies:

x = 10

Explanation

زیرک کا مطلب ہوتا ہے چالاک، عقلمند یا سمجھدار شخص۔

یہ لفظ کسی ذہین یا ہوشیار فرد کے لیے استعمال ہوتا ہے۔

Explanation

The original sentence is in simple past tense: "He published..."

The passive voice of a simple past sentence follows the structure: Object + was/were + past participle + by + subject

Therefore, "His second book was published by him..." is correct.

Explanation

Cell wall is not a part of animal cells; it is found only in plant, fungal, and bacterial cells.

Animal cells have a cell membrane, cytoplasm, and vacuole (though smaller than in plant cells).

Explanation

The sentence is in present perfect tense ("have lost"), so the passive voice should be in the form: has/have been + past participle.

"Our basket of chocolates has been lost by us" correctly matches this structure.

Explanation

بہادر شاہ ظفر کے اتالیق (استاد) شاہ نصیر تھے، جو دہلی کے مشہور شاعر تھے۔

انہوں نے بہادر شاہ ظفر کو شاعری کی تربیت دی۔

Explanation

قرآن کریم میں غزوہ تبوک کو "ساعۃ العسرۃ" یعنی تنگی و مشکل کا وقت کہا گیا ہے۔

یہ غزوہ سخت گرمی، قلتِ وسائل اور طویل سفر کے باوجود پیش آیا، اسی لیے اسے یہ لقب دیا گیا۔

Explanation

The equation is:

(y + 13)(y + a) = 0

Expanding it:

y^2 + ay + 13y + 13a = 0

y^2 + (a + 13)y + 13a = 0

For no linear term, the coefficient of y should be 0:

a + 13 = 0

a = -13